The explosion killed Allan Catipay, 15, and his brother, Alano, 14, and caused injuries to their mother Merle, 35, and sisters Marianne, 10, and Maryann, 12.
Police said Alano was tilling the cornfield in Sitio Sampinit, Barangay Libertad when he unearthed the corroded MK-29 fragmentation grenade.
Alano called Allans attention to his find, and the two toyed with the explosive.
Alano reportedly struck the grenade thrice with a stone, causing it to explode and killing them on the spot, police said.
Their mother and two sisters are confined at the Vicente Gustilo District Hospital in Escalante, 95 kilometers from this city. Antonieta Lopez