"This is the biggest discovery of World War II ammunition in the entire country," said SPO4 Pantaleon Estojero, chief of the regional police’s Explosive and Ordnance Division.
No one was reported injured in the explosion which residents of Barangay 64 in Calainpawan likened to an "Intensity 7 earthquake."
The blast, however, destroyed 50 houses, including the bungalow where the vintage bombs were dug up.
The 10-man ordnance team has unearthed at least 40 World War II bombs, each measuring 24 inches long and with a circumference of 56 millimeters.
Twenty-six of the bombs were immediately removed from the site and brought to the "explosives dam" of the ordnance division at Camp Ruperto Kangelon in Palo town.
Estojero said that based on their investigation, the site could contain over 250 bombs. His team also found 34 sacks of ammonium nitrate, a chemical used in making explosives.
Estojero said the retrieval operation may take 15 days. His division plans to ask Camp Crame to send additional bomb experts and equipment to be used in "scanning" the site before full-blast excavation begins.