NEW YORK (AP) - The London suicide bombers cooked up their explosives using mundane items like hydrogen peroxide, suggesting that "these terrorists went to a hardware store or some beauty supply store" for ingredients, according to New York City police.
Details from the July 7 London bombings emerged Wednesday at an unusually wide-ranging briefing given by the New York Police Department to city business leaders. A department spokesman later acknowledged that London officials had not authorized the briefing.
The briefing - based partly on information obtained by NYPD detectives who were dispatched to London to monitor the investigation - was part of a program designed to encourage more vigilance by private security at large hotels, Wall Street firms, storage facilities and other companies.
Police Commissioner Raymond Kelly warned the materials and methods used in the London attack were easily adaptable to New York.
"Initially it was thought that perhaps the materials were high-end military explosives that were smuggled, but it turns out not to be the case," Kelly said. "It's more like these terrorists went to a hardware store or some beauty supply store."
The NYPD officials said investigators believe the bombers used a peroxide-based explosive called HMDT, or hexamethylene triperoxide diamine. HMDT can be made using ordinary ingredients like hydrogen peroxide (hair bleach), citric acid (a common food preservative) and heat tablets (sometimes used by the military for cooking).
HMDT degrades at room temperature, so the bombers preserved it in way that offered an early warning sign, said Michael Sheehan, deputy commissioner of counterterrorism at the nation's largest police department.
"In the flophouse where this was built in Leeds, they had commercial grade refrigerators to keep the materials cool," Sheehan said, describing the setup as "an indicator of a problem."
Among the other details cited by NYPD officials:
- The bombers transported the explosives in beverage coolers tucked in the back of two cars to the outskirts of London.
- Investigators believe the three bombs that exploded in the subway were detonated by cell phones that had alarms set to 8:50 a.m.
- Similar "explosive compounds" were used in the attempted attack in London on July 21. However, the detonators were hand-activated, not timed.
Sheehan said the NYPD was troubled by information it had received about the bombers' links to "organizations," but he did not name any groups.
"We know those same types of organizations that they're affiliated with are very much present in New York City," he said. "That's something we're studying very, very carefully. ... This could happen here."
After the briefing, police spokesman Paul Browne claimed NYPD had clearance from British authorities to present the information about the July 7 attack, which killed 52 people. On Thursday, he said had been mistaken.
However, Browne insisted "all the information in the briefing was from open and unclassified sources."
The session at police headquarters in lower Manhattan was attended by officials from police departments and law enforcement agencies in Baltimore, Washington, D.C., Philadelphia and other jurisdictions. The officials were in the city discussing plans to beef up security along Amtrak's New York-Washington route.