ZAMBOANGA, Philippines – Gunmen ambushed a mayor's convoy in Jolo Island, a troubled part of the southern Philippines, on Thursday (August 2nd), killing three policemen and a civilian, AFP reported.

A report by the Xinhua news agency identified the mayor as Firhana Mohammed of the town of Omar in Sulu province. She was unhurt, but the town's police chief and two other officers escorting her were killed, regional police chief Senior Superintendent Antonio Freyra said.

A civilian in one of the vehicles was killed and five others were wounded, he added.

A police report in Manila said the attackers are believed to be supporters of a rival politician. The impoverished island is a stronghold of various armed groups including Muslim extremists, former rebels and private armies of powerful political clans.

Many of these clans employ gangs of armed followers to enforce their will and intimidate rivals and critics, with violence often rising as elections approach.

In the worst recent case of such violence, followers of a Muslim clan that dominated politics in one southern province in 2009 allegedly massacred 57 people to stop a rival's effort to run against the family in local elections.