4 police killed, others wounded in Mexico gang attack Prosecutors say four police officers have been killed and seven others wounded in a large-scale shooting attack in western Mexico

MEXICO CITY -- Four police officers were killed and seven others wounded in gang attacks in western Mexico, according to local officials, and two bystanders were being treated for wounds.

The Michoacan state prosecutors' office said attackers opened fire on one patrol vehicle and then twice ambushed reinforcements that were sent in to help on Sunday.

The office said three officers died in the attacks in the city of Zamora, and Mayor Martin Samaguey later said a fourth had died of wounds suffered in the shootings.

The prosecutors' office did not identify which gang was behind the attack in the city of Zamora. However, prosecutors said one of the attackers' trucks had been found and local media published photos of the pickup with the letters "CJNG" on its door.

Those are the Spanish initials of the violent Jalisco New Generation Cartel.

A video posted on social media around the time of the attack showed a convoy of pickup trucks and SUVs, apparently about two dozen, all with "CJNG" neatly painted on their doors or sides.

The dead and seven of the wounded were municipal police, who in most parts of Mexico rarely play a front-line role against drug cartels.

Municipal police are relatively lightly armed and are less well-paid and trained than their federal and state police colleagues. In many towns, they have been corrupted by drug gangs.

Samaguey, the mayor, said the city had been asking for help for some time.

"These have been difficult times," Samaguey wrote in a statement. "We have been urgently requesting assistance from state and federal authorities, while working with whatever we have and doing whatever we possibly can."