A group of more than 30 gunmen has stormed a drug rehabilitation centre in northern Mexico and opened fire, killing 19 people and wounding four others.
The rampage, the latest in a wave of violence linked to the narcotics trade, took place in the northern city of Chihuahua about midnight on Thursday.
The gunmen arrived aboard six trucks, according to a federal police official.
Climbing to the second floor of the Templo Cristiano Fe y Vida - the Christian Faith and Life Temple - they fired large-calibre weapons at patients and employees, killing 14.
They fatally shot another five persons and left a threatening message before fleeing.
At this time there are 19 deaths confirmed, the police official said.
The raid lasted little more than 10 minutes, according to residents living next to the centre.
Shortly afterwards, police and soldiers surrounded the area searching in vain for the perpetrators and ambulances ferried the wounded, including four reportedly in serious condition, to local hospitals.
Chihuahua state is the scene of a bloody struggle between drug cartels fighting for control of the lucrative trade in cocaine, mainly to the United States.
Authorities say rehab centres are often targeted by the cartels because they are used by individuals selling small quantities of drugs, and as a refuge from violence or rival gangs.
In September 2009 there were two similar attacks that left a total of 28 people dead in two drug rehabilitation centres in Ciudad Juarez.
Some 23,000 people have died in surging drug-related violence following the launch of a military clampdown on organised crime, involving some 50,000 troops, at the end of 2006.
Earlier this week, eight suspected members of the Beltran Leyva drug gang, among them two Colombian nationals, were killed in a clash with Mexican soldiers.