A grenade attack on New Year's Eve celebrations in the southern Philippines killed at least 10 people — including a 14-year-old boy — and wounded 32 others, an army official said Wednesday.

A man tossed the grenade at a crowded fireworks stall in the city of Tacurong in Sultan Kudarat province on southern Mindanao island, army Capt. Onting Alon said. Most of the casualties were holiday revelers.

Police launched a manhunt for the man seen lobbing the grenade.

No one has claimed responsibility, but authorities have blamed the separatist Moro Islamic Liberation Front, or MILF, for a series of bomb attacks and an ambush that have killed 30 people and injured dozens in the southern Philippines in the last two weeks.

The rebels, who have been fighting for three decades for Muslim self-rule in the region, have denied the charge.

"We deny all these baseless reports about MILF involvement in the attack," rebel spokesman Eid Kabalu said after the explosion. "We are not terrorists."

About 50 customers were at the stall buying firecrackers when the blast occurred around 9 p.m. local time at the city's busy square, witnesses said. Four people, including the teenage boy, died instantly, Alon said. The wounded were mostly injured from shrapnel.

It was the fifth bombing in central Mindanao since Christmas Eve, when a homemade bomb killed the mayor of Datu Piang town and 16 others. Police said the MILF was behind that attack.

Tacurong is a mainly Christian agricultural city at the heart of Sultan Kudarat, next to Maguindanao province, where the separatists have many bases.

Communist New People's Army rebels also have a presence in Tacurong, but they are not known to have staged attacks similar to Tuesday's.

The military and the Moro Islamic Liberation Front have accused each other of violating a 1997 truce. Peace negotiations between the government and the separatists were suspended in October 2001, but are expected to resume later this month in Malaysia.