Gunmen opened fired on a group of people at an auto body shop in the Gulf Coast state of Tabasco, killing nine people and badly wounding another, officials said Wednesday.
Tabasco had been largely spared the drug-related violence affecting Veracruz and Tamaulipas states, to the north.
Eight people were initially killed in the late Tuesday attack in the city of Cardenas, but a ninth victim died of his wounds on Wednesday. Another badly injured person is being guarded by police at a hospital.
Some of the victims may have been customers waiting for their cars at the shop.
Police said in a statement no one has been arrested and a motive in the killings has not been determined.
Cardenas city authorities on Monday found the body of woman along with a message warning the residents to stay indoors after midnight.
Meanwhile, gunmen ambushed and killed three police officers Tuesday in a suburb of northern city of Monterrey. Guadalupe city police said the officers were attacked with assault rifles and grenades.