MANILA, Philippines: Police say a grenade attack on an army outpost in the southern Philippines has wounded at least 37 people who were watching a nearby circus performance.

Police Senior Inspector Romeo Abler says a man hurled the grenade toward the outpost but it hit a protective net and bounced toward dozens of villagers watching a nearby circus late Saturday in Paquibato district in Davao city's rural outskirts.

Abler told The Associated Press by telephone Sunday that 37 villagers were wounded by the powerful blast and a stampede that followed. At least three were in serious condition in a hospital.

Communist guerrillas are active in the remote region but an investigation has not yet clearly pinpointed who may have carried out the attack, according to Abler.