Across northern Mexico, there have been increasing reports of mass shootings at parties, bars and rehab clinics.
In the worst such massacre this year, gunmen raided a drug-rehab center in the northern city of Chihuahua and killed 19 people last month. In January, gunmen barged into a private party in the border city of Ciudad Juarez and killed 15, many of them high school or university students. Relatives say the January attack was a case of mistaken identity, while state officials claim someone at the party was targeted, although they have not said who it was.
The killings in Torreon came three days after the first successful car bombing by drug cartels, an attack that introduced a new threat to Mexico’s raging drug war.