MANILA, June 26 (Xinhua) -- An investigation is underway to get into the bottom of Monday's clash in the Philippines between policemen and troops that killed six policemen and wounded nine others, a police report said on Tuesday.

Troops on patrol opened fire at patrolling police around 9:20 a.m. local time on Monday in a village in Santa Rita town in Samar province in the central Philippines, ensuing a 30-minute firefight that killed and wounded the policemen.

The report said both the government security forces were on combat patrol when the fatal "encounter" broke out.

No soldier was killed or wounded in the incident, the report said.

"A joint, thorough and impartial investigation is being conducted," said Maj. Gen. Raul Farnacio, an Army commander operating in the province known as a hotbed of insurgents.

Farnacio assured the public that the military and the police are "fully cooperating to shed light on the incident," adding that "appropriate actions" will be taken against the erring ground commanders.

"Rest assured that this unfortunate incident will not hamper the working relation of your Army and the police in the region," Farnacio said.