Manila  - A town mayor in the northern Philippines and three of his security escorts were killed in an ambush by unidentified gunmen, police said Thursday.

Raul Dela Cruz, 61, mayor of Rizal town in Cagayan province, 345 kilometres north of Manila, died while being rushed to hospital, according to Senior Superintendent Moro Virgilio Lazo.

Dela Cruz suffered gunshots to the head and body during the attack Wednesday evening along a highway in Solana town, said Lazo, the provincial police director.

Three of the mayor's security escorts died on the spot when the gunmen opened fire at the government bus they were riding in, he added.

Four other passengers were wounded in the ambush.

Lazo said police have set up checkpoints in the province in a bid to track down the unidentified assailants.

He added that investigators have not yet determined a motive for the killing, and were looking into whether the attack could have been politically motivated. (dpa)