According to the LA Times article on July 10, 2010, 19 people were gunned down in the city of Chihuahua in northern Mexico. The gunmen first posed as police before breaking into the rehab clinic and killing 19 people including recovering addicts and staff members. There is no clear cut motivation for the killings as of yet but it is likely tied to a vicious drug war being carried out by rival gangs and drug cartels.
There have been roughly 23,000 deaths linked to gangs and drug cartels in Mexico since 2006. It is believed that many cartels are using the treatment centers as recruiting centers by offering the recovering addicts drugs and threatening them with death if they refuse to join their operation.