MEXICO CITY (AP) — A fire in a drug rehabilitation center in the violence-plagued Mexican state of Guanajuato killed 12 people and injured at least three others, authorities said Sunday.

The fire broke out early Sunday in the town of San Jose Iturbe, where the municipal government said it was still investigating what caused the deadly blaze.

“We express our solidarity with the families of those who have been killed while they tried to overcome addictions,” the municipal government said in a statement, adding that it will help to pay for the funeral expenses of those killed.

Mexican media outlets reported that the victims of the fire had been locked up inside the rehab center.

Mexico’s privately run drug rehabilitation centers are often abusive, clandestine, unregulated and underfunded. They have been the targets of similar attacks in the past.

The industrial and agricultural state of Guanajuato has for years been the scene of a bloody turf battle between the Jalisco New Generation Cartel and a local gang, the Santa Rosa de Lima Cartel. Guanajuato has the highest number of homicides of any state in Mexico.

Mexican drug gangs have killed suspected street-level dealers from rival gangs sheltering at rehab facilities in the past.

In 2020, gunmen shot to death 27 people at rehab center in another city in Guanajuato, Irapuato. In 2010, 19 people were killed in an attack on a rehab center in Chihuahua, a city in northern Mexico. More than a dozen other attacks on such facilities occurred in the decade between those massacres.