Gunmen stormed a beer business in northern Mexico on Friday, killing 10 people in broad daylight and leaving some of the victims naked over an apparent gang feud, officials said.
Several armed men arrived in two vehicles before attacking people inside the beer distribution center in the municipality of Garcia, a suburb of the industrial hub of Monterrey, prosecutors said.
The "main line of investigation" is that the shooting was linked to a dispute between criminal groups, said Nuevo Leon state attorney general Javier Flores, adding that seven kilograms (15 pounds) of marijuana was found at the scene.
Seven people died on the scene and were found either naked or half-naked, Flores said. The three other victims died at a hospital.
The victims were "specifically targeted" in the attack, he said, adding that other distribution center workers were spared.
"We can't be sure that the victims were involved in criminal acts but by the way that they were attacked, it would appear they were," Flores said.
State investigators, who requested anonymity, said former members of the Zetas drug cartel used the location for their trafficking scheme.
In addition to the marijuana, investigators found a scale, an assault rifle and 10 bullet shells. Another official said the assailants stole 10,000 pesos ($650) in cash.
Garcia is the hometown of Jaime "El Bronco" Rodriguez, the former mayor who made international headlines this month when he became the first independent candidate to win a gubernatorial election in the country.
The Nuevo Leon governor-elect gained fame when he was mayor from 2009 to 2012 as he defied the ultra-violent Zetas cartel.
Rodriguez reacted to Friday's killing on his Facebook page, saying he was "sad and angry" and urged authorities to act quickly to find the perpetrators.
"They should not let the wave of violence return," he said.
Rodriguez says he survived two assassination attempts when he was mayor and that his daughter was briefly kidnapped when she was two years old.
Zetas leader Omar Trevino, alias "Z-42," was captured in March in another Monterrey suburb, the upper-class district of San Pedro Garza Garcia.
The Zetas are accused of being behind an arson attack against a Monterrey casino that left 52 people dead in 2010.
The gang, founded by military deserters, used to be the armed wing of the Gulf cartel until the two sides split in 2010, leading to bloody turf wars in Mexican states.
Mexico's border states are major drug routes to the United States and have endured some of the worst violence in cartel wars that has left more than 80,000 people dead and 22,000 missing across the country since 2006.