A drug-crazed man runs up behind a woman in San Francisco's Marina district and pulls her to the street as he tries to wrestle her purse away.
A group of young men surrounds a commuter on a Muni bus at Fifth and Market streets; they point a gun at him and demand his iPod.
A hooded man yells at customers in a pizzeria in Oakland's Oakmont neighborhood to put their wallets on their tables, as his partner waves a revolver.
More than 40 robberies occur every day in the Bay Area - and they are happening far more often than just a few years ago.
While recent high-profile restaurant robberies have citizens calling for police to crack down on commercial holdups, the total number of robberies in the nine-county region was up nearly 40 percent in 2007 compared with 2004, according to the FBI's most recent figures.
Some of the worst spots are busy hubs for commuters and shoppers, including the areas around the 12th Street BART Station in downtown Oakland, and San Francisco shopping districts at Fifth and Market streets and the Metreon at Fourth and Mission streets, according to a Chronicle analysis.
"Robberies are the soup du jour of crime," said David Kozicki, deputy police chief of Oakland, which has been hit hardest by the recent takeover robberies, in which armed thieves force customers and employees of restaurants to hand over their money. "I've heard from cities around the nation: Robberies are getting worse."
The Bay Area violence follows a national surge that some experts fear signals the end of a long downturn that began in the 1990s and has allowed once-crime-ridden areas to grow into trendy neighborhoods. Now some of those areas are starting to see old crime problems returning.
The Chronicle examined location records of more than 30,000 robberies in San Francisco and Oakland since 2004, as well as statistics for other Bay Area cities, and found a gloomy outlook:
-- Between 2004 and 2006, robberies spiked in the region, going from 11,264 a year to 15,698, then leveling off in 2007 at 15,646. Bay Area-wide statistics from the FBI aren't available for 2008. But, running counts in San Francisco and Oakland show both cities' numbers are higher this year.
-- Strong-arm robberies, in which the assailants used only bodily force, are the most prevalent. But in both San Francisco and Oakland, the percentage of robberies involving guns has crept up since 2005 - from 30 to 39 percent.
-- IPods, laptop computers and fancy cell phones are such hot items for robbers that some investigators suggest the increasing prevalence of these expensive, easy-to-sell accessories in public places may be a driving force behind the robbery surge.
-- Some of the areas that have seen the biggest increases in robberies are up-and-coming neighborhoods that had seemed to have risen above historical crime problems. These include Oakland's Rockridge district and neighborhoods in the lower hills, such as Oakmont and Glenview near Park Boulevard, and San Francisco's Glen Park.
Criminologists warn that the faltering economy probably will make matters worse.
"The steep economic downturn of 2007 and 2008 portends a crime rise that may dwarf recent increases," wrote University of Missouri-St. Louis criminologists Richard Rosenfeld and Brian Oliver, in a paper presented at a national criminal justice conference in July. "Local communities should plan for new crime increases in the years ahead."
San Francisco's biggest hot spot is the intersection of 16th and Mission streets, where police say drug-dealing activity and the heavy traffic coming in and out of the BART station combine to offer a perfect opportunity for muggings. There were 58 robberies reported there during 2007 and the first half of 2008. More than 70 percent of these were strong-arm robberies.
But, block for block, there is no denser concentration of robberies than in San Francisco's Tenderloin. The area of halfway houses and residence hotels is plagued with drug dealing, prostitution and drunkenness - and police say robberies go hand in hand.
The Tenderloin has six of San Francisco's 15 worst intersections for robbery and typically experiences about a robbery a day.
People involved in the drug scene are often both the perpetrators and victims of robberies there, police say. But others get hit as well, including residents from Southeast Asia and Central American whose numbers have recently increased in the neighborhood. Some mornings, police say, robbers set up at bus stops along Hyde Street to hit commuters.
In Oakland, the rough neighborhoods around the Eastmont Mall and the Fruitvale district are favored hunting grounds. In the Fruitvale area, police say day laborers are major targets of robbers looking for cash.
But other hot spots are transit or shopping hubs, where crowds mingle and, police say, robbers have lots of potential targets and getaway options.
In Oakland, the single worst hot spot is the intersection of Broadway and 13th Street near the 12th Street BART Station. In San Francisco, Halladie Plaza, the shopping area on Market Street near Fifth Street and a busy corner at Third and Market streets have similar characteristics.
San Francisco Robbery Lt. William Canning said these are locations where shoppers, tourists and commuters inevitably end up rubbing elbows with gang members, drug users and homeless people. The result can be volatile.
"These are transit corridors," said Canning. "You have a crossroads where all kinds of people come together. Unfortunately, that can be a useful environment to the criminal element."
Robbery Sgt. Shaughn Ryan said many of these spots - particularly the corner of Fourth and Mission streets, at the Metreon - are weekend hangouts for youths, who often form rat packs that target other youths.
Yet some of the neighborhoods that have seen the biggest increases in robberies are places that once seemed to have largely overcome crime.
Oakland's Oakmore neighborhood, where Joseph Radwan and his family decided to open the Red Boy Pizzeria earlier this year, seems a world away from the violence in many nearby East Oakland neighborhoods.
Nestled in the lower hills among winding streets and oak trees, it and the neighboring Glenview district have seen business boom with trendy new restaurants and cafes moving in along Park and Leimert Boulevards - during a time when crime was on the wane in both Oakland and the nation.
Yet on March 31, eight days after the restaurant opened, two juveniles wearing dark hoodies walked in just as the last two tables of customers were getting ready to leave before closing time.
"One guy went around the tables to the customers and said, 'Get all your cash and put it on the table.' The other guy just sort of swung his gun around," said Radwan, who manages the restaurant that is co-owned by his parents. "It was terrifying."
In Oakland as a whole, robberies increased by 23 percent between 2005 and 2007, but robberies in the lower hills police beats that encompass Oakmore, Glenview, Lakeshore and the Dimond district nearly doubled - going from 34 to 63. Similarly, the upscale Rockridge neighborhood in North Oakland saw robberies jump from 36 in 2005 to 68 last year. Oakland's crime numbers at the neighborhood level are not available for 2004 because of a change in the police department computer system.
"The crooks have realized we're easy marks," said Vivek Bhatia, a management consultant who moved to Rockridge in 2001 and has since become the neighborhood's self-appointed crime expert. After the huge surge in muggings there a couple years ago, he started a neighborhood Web site with monthly crime statistics and installed seven video cameras to guard his home.
His records show the number of violent crimes in the neighborhood have nearly tripled since 2005.
Bhatia said residents often open themselves to becoming victims by failing to take basic precautions, such as locking doors and keeping valuables out of sight. "Nobody wants to admit there's crime here, because it's hard to say, 'I just spent big money to live in a neighborhood with crime problems.' "
"If I'm a robber, how am I going to grow my business? This was an untapped market. "
Similarly, crime figures in San Francisco's Glen Park and Diamond Heights neighborhoods risen far faster this year than the city overall. The two neighboring areas in the Ingleside police district had 20 robberies in the first half of this year, compared with 16 in all of 2005.
Starting in late 2005, police began to notice that robbers were more prevalent and younger - and they had their eyes on high-tech gadgets. Groups of youths as young as 13 or 14 would surround someone and grab the victim's iPod.
"We noticed a significant rise in juvenile crime," said San Francisco Police Capt. John Loftus, who headed the robbery division when the rise in crime started. "I'm not sure if there were more kids or whether they just weren't behaving."
In fact, researchers say the number of teenagers in the population is relatively level.
San Francisco's Canning, who now heads the robbery unit, said there have been cases where young girls were the robbers.
Loftus and other officers speculated that a new generation of gadgetry hitting the streets at the same time might have increased the temptation.
"The iPods came out around this time and wireless became popular. You'd have people sitting in cafes pecking away at $4,000 or $5,000 pieces of equipment. That's a very desirous piece of equipment for a kid to have."
Since the beginning of the year, Canning said his department has recorded robberies involving thefts of 37 iPhones, 122 other cell phones, 100 portable music players and 56 laptops.
The robbers "either keep them or sell them for quick cash," said Canning. "If I steal your $2,000 laptop and get $100 for it, I'm happy."
Statistics show the percentage of robberies involving guns also increased since 2005.
In Oakland, armed robberies are far more prevalent than in San Francisco. In the first five months of 2008, guns were involved in 55 percent of Oakland's robberies, up from 41 percent in 2005. In San Francisco, robberies involving guns climbed from 21 to 25 percent, according to The Chronicle's analysis.
The robbery on a Muni bus at Fifth and Market streets on Aug. 13 was the kind of holdup police report again and again.
Six 17-and-18-year-olds surrounded a man in his 20s as he was preparing to get off the 71-Haight bus at 8:30 in the evening. One of the robbers pulled a gun and demanded his iPod.
The man jumped off the bus and reported the robbery to police at the nearby Powell Street BART station, and the robbers continued riding the bus. BART Police called the San Francisco Police Department, which teamed up with Muni to track down the bus as it headed toward Haight Street. San Francisco officers caught up with the bus on Haight Street, arrested three suspects and detained three others.
The 24 hours beginning at 7:30 p.m. on July 30 show the kind of mayhem facing police on an almost daily basis.
In rapid succession, two purse snatchers violently attacked three women walking separately in the early evening in the Marina in San Francisco. In the first attack, the robbers grabbed a woman's purse and then forced her to the ground. Eight minutes and two blocks later, the robbers did the same thing to another woman, pushing her to the ground in the middle of a street. In the third incident, the robbers' getaway vehicle hit their victim, leaving her with serious head injuries.
Police quickly nabbed two suspects - one of whom admitted committing the crimes, saying he and his accomplice needed money to buy crack cocaine.
Two hours later, near Harrison and 20th streets in the Mission District, two men were shot when they resisted a robbery attempt by another male. One sustained life-threatening injuries - the robber got away.
In the East Bay 6:15 the next morning, two men went on a robbery spree that included five street muggings in Oakland and Emeryville. In one of the robberies, at the Wells Fargo bank on Piedmont Avenue, the assailants allegedly targeted a woman who was eight months pregnant and punched her in the stomach to get her cash. The robbers were nabbed in Berkeley after a witness reported them trying to use a stolen credit card at a gas station.
In addition to these high-profile cases during the 24 hours, there was a taco truck holdup in San Francisco's Mission District, an armed holdup in downtown Oakland at 11th Street and Broadway and two other strong-arm robberies in Oakland.
"We get so many of these cases, we just get buried," said Police Sgt. Larry Krupp, who heads Oakland's robbery unit.
But for the robbery victims, the experience can be life-shattering.
Terri, one of the women accosted by the purse snatchers in the Marina on July 30, said the most frightening thing was that this happened in broad daylight in one of the safest neighborhoods in San Francisco. Yet no one came to her aid as she screamed and struggled with her attacker.
"As a single woman living in the city, I always thought if I screamed loud enough somebody would come and help me," said Terri, who asked that her last name not be used because she fears retribution from the two suspects who are facing robbery charges.
"But the reality is nobody is going to come. It made me see the city in a whole different light."