Gunmen carrying assault rifles opened fire on a crowd celebrating in a house after an amateur baseball game in northern Mexico, killing 10 including a six-year-old girl, authorities said on Monday.
Some 30 people were in the house near the field late Sunday on the outskirts of Ciudad Juarez, which borders the US state of Texas, when two gunmen stormed the place and fired AK-47 rifles, officials said.
The dead included eight men, a woman and the child, the Chihuahua state prosecutor's office said. Authorities picked up 31 bullet casings at the crime scene.
"Two assassins entered the home and fired," Chihuahua state attorney general Carlos Manuel Salas told reporters, citing a preliminary investigation.
"The victims were honorable, decent people who came to celebrate a baseball victory," Manuel Salas said.
The authorities did not disclose a possible motive for the attack.
The shooting took place in Loma Blanca, a town outside Ciudad Juarez where federal police killed a Sinaloa drug cartel capo, Gabino Salas Valenciano, in August.
Authorities said earlier in September that they had detained the alleged leader of the Juarez cartel, Alberto Carrillo Fuentes.
Ciudad Juarez was once considered the world's murder capital, with more than 3,000 people killed in 2010 alone amid a turf war between the Juarez and Sinaloa cartels, but the homicide rate has been falling in the past three years.
Carlos Gonzalez, the spokesman for the state prosecutor's office, said the victims in the Loma Blanca massacre had no links to organized crime.
"They were students, farmers, workers," he said.
Survivors said one of the gunmen shouted that they were part of La Linea, an armed wing of the Juarez cartel, and that they had retaken control of the area.
A police and military operation was launched late Sunday to find the killers but no arrests have been reported so far.
The brutal attack revived memories of the massacre of 15 people in Villas de Salvarcar in 2010, when gunmen opened fire on students having a party in the Ciudad Juarez suburb after apparently confusing them for a rival gang.