MANILA, Philippines -- A powerful explosion ripped through three floors of a shopping mall in the heart of Manila's financial district Friday, killing eight people, injuring scores and sending police and troops on the highest state of alert.
President Gloria Macapagal Arroyo said "circumstances indicate it is highly probable that it was caused by an explosive device." The same mall was targeted by a bombing in 2000.
She said police and the military went on the highest alert and deployed an additional 2,000 personnel to secure public areas "to prevent a similar occurrence."
The afternoon explosion at the glitzy Glorietta 2 mall toppled roofs, destroyed walls, and sent debris crashing onto cars outside.
At least eight people were killed and about 130 were wounded, officials said.
Police Chief Inspector Raynold Rosero, deputy chief of the Philippine Bomb Data Center, said a bomb squad took swabs to identify the explosive responsible for the blast in Makati.
He said no bomb parts or fragments such as a detonating cord, switch or power source were immediately found in the area, which was damp with water possibly due to broken pipes.
National Security Adviser Norberto Gonzales said authorities were looking into a possible terrorist attack, but "there is no conclusive evidence yet."
Mario Em, a taxi driver, said he had just dropped two women off at the mall when the blast hurled the passengers against his vehicle, killing them instantly.
He said he pulled one of the victims, who was pregnant, from underneath his car.
Officials said the shock waves from the blast, which appeared to have originated near the delivery loading dock, shot through three floors of the mall as well as sideways.
Mae Ann Sison said her sister, Angelica Cortez, was on an escalator going down from the second floor when the blast tossed her in the air.
"She landed on the escalator and her right foot got caught in the escalator chain and she was hit by glass shards from shops around her," Sison said, adding a chunk of concrete hit her sister's head.
Al-Qaida-linked militants, who have waged a yearslong bloody bombing campaign in the southern Philippines, have targeted Manila before.
Makati city councilor Jejomar Binay Jr. said a bombing at the same mall in May 2000 that wounded 13 people was the work of Muslim extremists. Five months later, five nearly simultaneous bombs around Manila blamed on the al-Qaida-linked Abu Sayyaf and the Jemaah Islamiyah network killed 20 people and wounded about 100 others.
In 2004, Abu Sayyaf militants blew up a passenger ferry in Manila Bay, killing 116 people in the country's worst terrorist attack. The following year, four people were killed and dozens wounded when a bomb exploded on a Makati bus and two southern cities.
Several months ago, authorities were alerted to an alleged terror plot to plant bombs in Manila's business districts of Makati and Ortigas, said a government counterterrorism official, speaking on condition of anonymity because he was not authorized to speak to the media.
People inside the mall scampered toward the exits when the blast shook the mall.
"One man who was in front of me was already dead. There was a child, but we don't know where the child is now," said Dennis Inigo, who was shopping at the time.
"The man's wife was with me a while ago, and her leg was shattered. Many people were falling on top of each other," he said. "It was loud, and then it became dusty."
Associated Press writers Teresa Cerojano and Jim Gomez contributed to this report.