Updated

The Mexican army says two soldiers were shot to death and a third wounded when troops investigating a pipeline fuel theft came under fire from gunmen using townspeople as a human shield.

The confrontation late Wednesday in the central state of Puebla marked an escalation of recent conflicts in which fuel thieves have largely taken control of some towns.

The defense Department said Wednesday a patrol was dispatched to the town of Palmarito to investigate reports of an illegal pipeline tap.

When soldiers arrived, they came under fire from assailants who took cover behind a group of women and children.

The soldiers did not return fire because the attackers were using the townspeople as a human shield.

The army is also increasingly facing civilian resistance in drug eradication patrols.