The bodies of 23 people were found hanging from a bridge or decapitated and dumped near city hall Friday in the border city of Nuevo Laredo, where drug cartels are fighting a bloody and escalating turf war.

Authorities found nine of the victims, including four women, hanging from an overpass leading to a main highway, said a Tamaulipas state official who spoke on condition of anonymity because he was not authorized to provide information on the case.

Hours later, police found 14 human heads inside coolers outside city hall along with a threatening note. The 14 bodies were found in black plastic bags inside a car abandoned near an international bridge, the official said.

The official didn't release the contents of the note, or give a motive for the killings. But the city across the border from Laredo, Texas has recently been torn by a renewed turf war between the Zetas cartel, a gang of former Mexican special-forces soldiers, and the powerful Sinaloa cartel, which has joined forces with the Gulf cartel, former allies of the Zetas.

Local media published photos of the nine bloodied bodies, some with duct tape wrapped around their faces, hanging from the overpass along with a message threatening the Gulf cartel.

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Interior Secretary Alejandro Poire met with Tamaulipas Gov. Egidio Torre Cantu on Friday and agreed to send more federal forces to the state, according to a statement from Poire's office.

Nuevo Laredo was the site of a 2003 dispute between the Sinaloa and Gulf cartels that set off a wave of violence that has left thousands dead and spread brutal violence across Mexico. That year, then-Gulf cartel leader Osiel Cardenas was arrested and accused drug lord Joaquin "El Chapo" Guzman, sensing weakness , tried to move in on Nuevo Laredo, unleashing a bloody battle.

The city of tree-covered plazas and hacienda-style restaurants was transformed as the Zetas, then working as enforcers for the Gulf cartel, and Sinaloa cartel fighters waged battles with guns and grenades in broad daylight.

Killings and police corruption became so brazen that then President Vicente Fox was forced to send in hundreds of troops and federal agents, and the only man brave enough to take the job of police chief was gunned down hours after he was sworn in.

The Zetas won that fight and have since ruled the city with fear, threatening police, reporters and city officials and extorting money from businesses. They broke off their alliance with the Gulf cartel in 2010, worsening the violence across northeast Mexico.

But last month, 14 mutilated bodies were found in a vehicle left in the city center. Some media outlets reported that the Sinaloa cartel took responsibility for those bodies and in a message allegedly signed by its leader, Guzman, said the group was now back in Nuevo Laredo "to clean" the city.