Manila, Philippines ? A powerful blast ripped through three floors of a shopping mall in the heart of Manila’s financial district Friday, killing nine people and wounding more than 100, authorities said.

Police bomb investigators told President Gloria Macapagal Arroyo at a Cabinet security meeting covered live on local radio that they had detected the high explosive RDX at the site of the blast.

“It’s a bomb, but as to what kind of bomb, we are still trying to determine,” national police chief Avelino Razon told The Associated Press. “Likely it’s a terrorist attack, but what terrorist group, we have no indicator.”

Al-Qaida-linked Abu Sayyaf militants have waged a yearslong bombing campaign in the southern Philippines in their aim to establish a separate state for the majority Muslims in the region. Abu Sayyaf and the Indonesia-based Jemaah Islamiyah network have also launched attacks in Manila.

National Security Adviser Norberto Gonzales stopped short of directly blaming Abu Sayyaf, but noted that the group has aired appeals on the Internet for international support from jihadist groups.

“What is more ominous here is they may be planning a bigger attack,” Gonzales said on local radio. “They will first show a sample. That means that while the bomb yesterday already was powerful, it is still just a sample.”

Thirteen people were wounded when the same mall was bombed seven years ago, an attack officials said was the work of Muslim extremists.

The Friday afternoon explosion at the glitzy Glorietta 2 mall toppled roofs, destroyed walls, and sent debris crashing onto cars outside.

Before dawn today Red Cross volunteers recovered the body of a man, the ninth fatality, who was buried under piles of rubble inside the mall. The Red Cross reported at least one more person remained missing.

Law enforcement, Red Cross and local government officials offered conflicting numbers of wounded, ranging from 113 to 129.

Arroyo said the military went on the highest alert after the explosion and deployed an additional 2,000 personnel to secure public areas “to prevent a similar occurrence.”

Razon said he has ordered additional road check points and deployed more officers to secure malls, shopping centers, airports and seaports, and bus terminals.

Police Chief Inspector Raynold Rosero, deputy chief of the Philippine Bomb Data Center, said no bomb parts or fragments such as a detonating cord, switch or power source were immediately found in the area, which was damp, possibly because of broken pipes.

Officials said the blast, which appeared to have originated close to the mall’s ground-level loading dock for delivery vehicles, ripped through three floors of the mall, covering shops and restaurants with dust, glass splinters and other debris.