ZAMBOANGA, Philippines  - Gunmen ambushed a mayor's convoy in a troubled part of the southern Philippines, killing three police escorts and a civilian, officials said Friday.
The town official was unhurt in the attack on Jolo island on Thursday, but the town's police chief and two other officers escorting him were killed, said regional police chief Senior Superintendent Antonio Freyra.
A civilian in one of the vehicles was killed and five others were wounded, he added.
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.