Gunmen stormed a party in northern Mexico on Sunday and massacred 17 people, authorities said.
The assailants arrived at the gathering in the city of Torreon in several cars and opened fire without saying a word, the Coahuila state Attorney General's Office said in statement. At least 18 people were wounded.
Several of the victims were young and some were women, but their identities and ages had not yet been determined.
Television footage showed the patio of the house streaked with bloodstains and white plastic chairs overturned beneath a party tent decorated with pictures of snowmen. Police found more than 120 bullet casings at the scene, most of them from .223-caliber weapons.
Investigators had no suspects or information on a possible motive.