A police officer and four civilians were killed by gunmen in two separate incidents in the northern Mexican state of Chihuahua, authorities said Thursday.

Here in Ciudad Juarez, a crime-wracked metropolis just across the border from El Paso, Texas, assailants in several vehicles opened fire on municipal cops responding to what turned out to be a false report of a road accident.

One officer was killed and several others wounded, a source in the Juarez police department said.

Three passers-by also received gunshot wounds, while a child was hurt when he was struck by the car of a state agent rushing to the scene of the shooting.

Earlier, four men were slain at a nightspot in Chihuahua city, the state capital.