At least three people were killed in a grenade explosion Saturday night in the southern Philippine province of Sarangani, local police said Sunday.

The blast, which occurred shortly after 7:00 p.m. (1100 GMT) at the heart of Maasim town, also wounded more than 20 others, police said.

Local Bombo radio station reported that an unknown man threw a grenade at crowd in the plaza celebrating the town's 37th Foundation Day.

Security forces are yet to determine the group's involvement behind the attack in the area where there are active Muslim separatist rebels fighting for independent Islamic state.

Source: Xinhua