An armed gang attacked a drug rehabilitation centre in the city of Chihuahua overnight Friday, killing 19 youths and injuring at least two others there, prosecution officials said.
They said the centre was attacked by between 25 and 30 armed men.
The head of the police intelligence unit Saul Hernandez confirmed that the attack, the third of its kind in eight months, occurred at around 11 pm (0500 GMT) at the Fe y Vida (Faith and Life) centre.
In September last year, an armed gang killed 17 youth at another rehabilitation centre and two weeks later another gang killed a further 10 at another centre.
The authorities have attributed the killings to revenge attacks between rival drug-smuggling gangs, in particular the Mexicles and Aztecas gangs.
