The clinic attacks have been blamed on rival drug gangs
Gunmen have carried out another attack on a drugs rehabilitation centre in the Mexican city of Ciudad Juarez, killing 10 people and injuring two others.
The shooting follows the deaths of 18 people in an attack on a separate rehab centre in the same city this month.
Such shootings have been blamed on drug traffickers who accuse the clinics of protecting dealers from rival gangs.
A vicious inter-gang drug war in Ciudad Juarez has seen some 1,400 drug-related deaths so far this year.
Thousands of extra police and troops have been deployed in the city, which is on the US border, to try to stem the inter-gang violence.
The latest killings took place at the Anexo de Vida clinic.
Vladimir Tuexi, a spokesman for the Chihuahua state attorney, said the 10 people who died late on Tuesday night were shot as they finished praying before going to bed, reported Reuters news agency.
Earlier this month, Chihuahua state security minister, Victor Valencia de los Santos, said that rehab centres had become the breeding ground for criminal gangs.
"In this type of places, the drug cartels are recruiting youngsters from 17 to 23 years of age," he was quoted as saying by Mexico's El Universal newspaper.
The rival drugs cartels are embroiled in a vicious turf war over control of highly lucrative smuggling routes into the United States.