At least 17 hidden graves were uncovered in Guerrero state, an isolated mountainous area in Mexico, CNN reported Friday. The location is infamous for drug-related violence. Officials are still searching the area to see if they can expose more clandestine graves.

Authorities uncovered 32 bodies, 31 men and 1 woman, and nine severed heads Thursday. The victims have not yet been been identified. Police made the discovery after they were given a tip about kidnappings. They also found a cooler with human body parts, abandoned vehicles and ammunition clips.

“The discoveries are terrible,” a security spokesperson said, according to the BBC.

NBC News wrote that drug cartels are likely responsible for the violence. They have been involved in a wave turf battles, kidnappings and blackmail and it’s common for drug gangs to behead their victims.

“Faced with public disturbance generated by organized crime and armed civilian groups, we are responding with immediate action to protect citizens who are alien to the confrontations between criminal groups actions,” Guerrero Gov. Héctor Astudillo said in a press release Thursday.

Guerrero is the most violent state in Mexico. It is also a prominent opium manufacturer. There were more than 1,800 reported homicides between January and October 2016, the BBC added.

“The large cartels have become small criminal gangs, and they share one characteristic: the extreme and irrational use of violence,” Robert Alvarez, Guerrero Coordinating Group spokesman, told MVS Radio this week. “Here, there is a phenomenon.”

It’s unclear how long the remains were buried. They were taken to the state capital of Chilpancingo to be identified. No arrests have been made.

Mexico Graves Dozens of bodies were found in unmarked graves in Mexico. Photo: Getty Images

Follow me on Twitter @mariamzzarella