Police killed four gunmen in a shootout in Coahuila, a state in northern Mexico, prosecutors said.

The shootout occurred around 3:20 p.m. Monday in the city of Acuña, where Coahuila Attorney General's Office special weapons and tactics unit officers were on patrol.

Four gunmen riding in a vehicle opened fire on the officers, who engaged them in a shootout, the Coahuila Attorney General's Office said in a statement.

Army troops, crime scene investigators and other AG's office agents secured the area where the shootout occurred, officials said.

A van with Texas tags and three AK-47 assault rifles were seized by investigators, the AG's office said.

Investigators are "working to identify the bodies to verify if they are those of inmates who escaped from the Piedras Negras penitentiary on September 17, 2012," the AG's office said.

The escape from Piedras Negras, according to officials, was orchestrated by the Los Zetas cartel, one of Mexico's most violent and powerful criminal organizations. EFE