Updated

Seven people including two police officers have been killed in what Mexican authorities call an ambush of a convoy in the southwestern state of Michoacan.

The state Public Safety Department and Prosecutor's Office say three more officers were wounded in the clash early Tuesday.

Police were guarding a truck and a pickup loaded with scrap metal heading to the city of Apatzingan. Officials say there was a sudden hail of bullets and grenades from dozens of attackers about an hour after midnight.

Authorities say the five civilians who died were burned when their vehicles were set on fire by grenades.

There were no immediate arrests.

The area around Apatzingan was a stronghold of the Knights Templar, a drug cartel whose disintegration has left smaller factions to war over turf.