Police in Mexico say a group of armed men raided a drug rehabilitation facility and opened fire, killing 19 people and wounding several others.
Officials say the rampage took place late Thursday at the Faith and Life center in the northern city of Chihuahua.
The French news agency quotes a police official on Friday as saying 30 gunmen were involved in the attack. The report says the assailants fired large-caliber weapons at patients and employees before fleeing.
The motive for the attack is unclear.
Mexico's Chihuahua state, where the city of Chihuahua is located, is home to major drug cartels, and drug-related violence is frequent.
Some information for this report was provided by AP and AFP.