At least 13 people, including a policeman, were injured when an explosion occurred in front of a church in North Cotabato while a Christmas Eve mass was ongoing.

Initial report from Police Regional Office 12 said the incident happened at around 9:28 pm after an unidentified male suspect threw a grenade under the parked patrol vehicle of the Midsayap Police Station.

The blast occurred 30 meters away from Santo Nino Church while a mass was ongoing.

The victims, who were attending the mass, were immediately brought to Cotabato Regional and Medical Center in Cotabato City.

The police patrol car and two private vehicles were also heavily damaged.

The Army's Explosive and Ordinance Disposal team identified the explosive as an M61 US fragmentation grenade.

Authorities have been investigating the incident as no group has so far claimed responsibility for the attack. Ella Dionisio/DMS