Suspected drug gang hitmen armed with machine guns stormed a private party in the northern Mexican city of Torreon, killing at least 17 people in one of the deadliest attacks in Mexico's drug war, police have said.
Five vehicles were driven up to the party in a walled patio and garden on the outskirts of the city in Coahuila state, before the armed men smashed down the door and opened fire on party-goers, the state prosecutors' office said.
A source with the state police department said witnesses reported hearing assailants shout "kill them all" before they opened fire on Sunday.
The prosecutors' office said 18 people were injured in the attack.
Authorities said they found more than 100 bullet casings fired from automatic weapons following the massacre.
'Shot everything that moved'
An official with the state prosecutor's office said the armed men "came in, opened fire and shot against everything that moved".
They escaped and no arrests have been made, the prosecutors office said in a statement.
Sunday's attack brings the number of shooting victims in Mexico over the weekend to at least 50.
It was not immediately clear who was responsible for Sunday's attack, but the area is a key transit point for drugs heading into the US and the scene of a showdown between the Sinaloa cartel led by Joaquin 'shorty' Guzman, Mexico's most wanted man, and the Zetas gang from the country's northeast.
On Saturday, suspected cartels detonated a car bomb that killed at least four people, the first attack of its kind in Mexico's drug war, in Ciudad Juarez, another northern border city.
El Diario, a newspaper in Ciudad Juarez, said that officials from the Federal Bureau of Investigation (FBI) and other US agencies are investigating the bombing. US and Mexican officials would not comment on the allegations.
More than 26,000 people have been killed in drug violence in Mexico, mostly in the north, since Felipe Calderon, the president, took office and initiated a crackdown on drug cartels in 2006.