The bomb exploded in the middle of the vehicle as it was loading passengers at a bus terminal near a market, said Zamboanga City police Chief Inspector Joel Tuttuh.

He said the suspects weren't known but could include the militants, who set off a car bomb in Zamboanga earlier this year near another bus terminal, killing two people and wounding more than 50 others.

Tuttuh said at least one of those wounded in Friday's blast was in serious condition after losing an arm and a leg.

"The [improvised explosive device] could have come from the Abu Sayyaf, disgruntled employees or competitors," he said by telephone from Zamboanga.

One of the bus owner's buses in the nearby island province of Basilan also was the target of a bomb attack, but Tuttuh could not immediately give details of that incident.

He said bomb squads from the police and the military, who were inspecting the site, could not immediately say what type of explosive was used. The militants frequently use unexploded mortar shells as the main charge for their homemade bombs.

The Abu Sayyaf, which was recently declared a terrorist group by a Philippine court and is also on Washington's lists of terror organizations, has about 400 gunmen under several factions operating in Basilan and nearby areas.

Aside from bombings, the group is also notorious for beheading hostages, ransom kidnappings of Filipinos and foreigners, and extortion.(++++)

Popular

RI, Australia strengthen partnership on taxing crypto assets

Analysis: Indonesia denies normalization with Israel to enter OECD

Citroen to produce electric cars in Indonesia