At least 26 people were wounded when two men on a motorcycle hurled a grenade into a group listening to a street music performance in the southern Philippines, a local police chief said on Wednesday.
The victims were watching a live band perform late on Tuesday outside local fastfood restaurant Jollibee in Isabela, the capital city on the remote southern island of Basilan, Albert Larubis, the city police chief, told reporters.
"We're still gathering information to establish the motive for the attack," Larubis said, adding 26 people were hurt.
"We still have no lead. Nobody can identify the two men who lobbed the grenade. About 16 remained in the hospital because they require more treatment for shrapnel wounds."
The blast came nearly a week after crude bomb attacks in two shopping malls in another southern city killed two people and wounded 27. Four more bombs had been found and defused in three other urban centres on the southern island of Mindanao this week.
Salik Macapantar, provincial police chief in Basilan, said there was speculation the small Islamic militant group Abu Sayyaf could be behind the grenade attack because it has been trying to extort money from businesses around the area.
"We have two theories," Macapantar said. "It's either part of an extortion operation by the Abu Sayyaf or it was a simple case of personal grudge."
The al Qaeda-linked Abu Sayyaf is active on the island and authorities blame them for a number of criminal activities, such as kidnap-for-ransom, robbery and extortion, arson, bombings and piracy.
Basilan is the stronghold of the 300-member Abu Sayyaf, believed responsible for the worst militant attack in the Philippines, the bombing of a ferry in 2004 in which at least 100 people were killed.