TAYABAS CITY, Philippines -- A high school student was killed and two others seriously injured when a rifle grenade they had found earlier accidentally exploded, police said Saturday.

A police report identified the victim of the explosion, which occurred Thursday afternoon in the village of Ilasan, as Roy John Pecito, 17, who was declared dead on arrival at the Quezon Medical Center in Lucena City.

His two companions, Marvin Luce, 15, and Nonilon Labado Sabadilla, 39, suffered serious injuries in different parts of the body.

Police said the victims were inside the house of Pecito when suddenly the M203 grenade which they found earlier in a forested area of the village exploded.

Neighbors helped the victims but Pecito expired before he reached the hospital.