Gunmen killed at least 17 people at a drug rehabilitation centre in the northern Mexican city of Ciudad Juarez, officials said on Thursday.
Five other people were also wounded in the attack at the El Aliviane drug treatment centre, prosecutors said.
The gunmen arrived in at least two vehicles and opened fire at the patients after entering the building. The injured were rushed to hospitals. This was the second attack on a drug rehab centre in Ciudad Juarez this year.
On June 1, five people were killed and three others wounded in a similar attack at another drug rehab facility in the city.