Guanajuato, a region in central Mexico, has become one of the principal flashpoints of surging gang violence which President Andres Manuel Lopez Obrador has promised to quell.
But despite lockdown measures imposed to combat the coronavirus outbreak, homicides continue to test record levels.
The state government said in a late Saturday statement that according to preliminary findings, three unidentified assailants shot up the rehab center in Irapuato, an industrial hub south of the state capital, also named Guanajuato.
Meanwhile, police are also investigating the killing of three men shot dead in a separate attack on Saturday in the city of Celaya, southeast of Irapuato, the state government said.
Rehab centers have previously been targeted by criminal gangs waging turf wars for control of the drug business.
In September 2017, at least 14 people were killed and several wounded in an attack by suspected gangsters on a drug rehab center in the northern city of Chihuahua.
