An assailant was killed when Mexican marines responded with gunfire after the occupants of a car shot at their helicopter, authorities said.

The confrontation took place Thursday in the western state of Michoacan, where Federal Police and military forces have been deployed for more than two months amid conflict between a powerful drug cartel and local militias.

The marine helicopter was on patrol over the municipality of Arteaga when it came under fire from the occupants of a white Mercedes-Benz.

The chopper descended and the marines returned fire, killing one of the vehicle's occupants, Michoacan Public Safety Secretary Carlos Hugo Castellanos Becerra said on Twitter.

"No element of the navy was wounded, and there was no crash of the aircraft," he said, correcting his own earlier messages about a crash.

Mexico's government sent federal security forces into Michoacan in mid-January to clamp down on the Caballeros Templarios (Knights Templar) drug cartel and bring the local armed self-defense groups under the formal control of the military. EFE