At least 14 people were killed and 8 injured Tuesday night in northern Mexico when an armed group opened fire in a drug addiction rehabilitation center, local police said.

In a statement security officials in the city of Chihuahua said "an armed group entered the Uniting Families rehabilitation center," attacking those inside with assault rifles.

First responders arrived on scene to care for the wounded in the center, where some 25 people were estimated to have been during the attack.

The state of Chihuahua, which borders the United States, has endured some of the worst violence in Mexico's decade-long militarized battle against drug trafficking.

In the past decade at least half a dozen attacks have taken place in rehabilitation centers, and according to authorities are generally perpetrated by gang members settling scores with rivals hiding in the centers.

Since the Mexican government launched its war on cartels in 2006, more than 200,000 people have died or disappeared amid the violence.