CULIACAN, Mexico – Gunbattles between rival gangs killed 18 people in a northeastern Mexican town Monday, a day after seven police officers and an inmate died in an ambush of a convoy transporting prisoners in western Mexico.

The fighting in the town of Abasolo erupted Monday morning and left at least 18 people dead, the Tamaulipas state government said in a three-sentence statement that offered no details. It said state and federal security forces had arrived in the town to restore order and investigate.

In northwestern Sinaloa state, meanwhile, gunmen swarmed a convoy transporting two prisoners, shredding three police vehicles with bullets and killing seven officers and one inmate, Sinaloa state Attorney General Marco Antonio Higuera said Monday. Six officers and the second inmate were wounded.

Mexican authorities say the Sinaloa and Gulf cartels made a pact last year to destroy the Zetas.

Federal police, meanwhile, said a newly captured leader of the Zetas drug cartel revealed it has a non-aggression pact with three other gangs — the Juarez, Beltran Leyva and Arellano Felix organizations. While the four gangs are not known recently to have been fighting major turf wars with each other, it was the first mention of a formal truce between them.