Twenty-four people have been killed and seven others injured after gunmen opened fire at a drug rehabilitation centre in Mexico.
Police in the north-central state of Guanajuato said the attack occurred in the city of Irapuato.
Three of the seven who were injured in the attack are in a serious condition, police said.
Guanajuato is the scene of a bloody turf battle between the Jalisco cartel and a local gang, and the state has become the most violent in Mexico.
No motive was given for the attack, but Governor Diego Sinhue Rodriguez Vallejo said drug gangs appeared to have been involved.
"I deeply regret and condemn the events in Irapuato this afternoon," the governor wrote. "The violence generated by organised crime not only takes the lives of the young, but it takes the peace from families in Guanajuato."
Mexican drug gangs have killed suspected street-level dealers from rival gangs sheltering at such facilities in the past.
It was one of the deadliest attacks on a rehab centre since 19 people were killed in 2010 in Chihuahua city in northern Mexico. More than a dozen attacks on such facilities have occurred since then.
Mexico has a history of problems with rehab centres because most are privately run and underfunded.
The Government spends relatively little money on rehabilitation, often making the unregistered centres the only option available for poor families.
