A suicide bomber blew up an explosives-laden car at a checkpoint in Yemen's restive southern province of Abyan on Monday, killing four pro-army gunmen, a military source said.
"Four of our men were killed when a suicide bomber detonated a car full of explosives at a checkpoint between Loder and Shaqra," in Abyan, the source said on condition of anonymity.
The militiamen from the Popular Resistance Committees are mainly armed local residents fighting alongside the Yemeni army against Al-Qaeda militants.
Yemeni forces launched an all-out offensive on May 12 aimed at reclaiming Abyan's capital Zinjibar and several other towns and cities in the province lost to Al-Qaeda over the past year.
Since the assault began, at least 391 people have been killed, according to an AFP tally compiled from official statements, including 285 Al-Qaeda fighters, 66 military personnel, 22 local militiamen and 18 civilians.