MEXICO CITY —  Gunmen identified as local police officers opened fire on a group of revelers returning from a weekend dance in central Mexico, killing seven people, including two children, in what authorities described as a case of mistaken identity.

At least five municipal policemen were among an estimated 10 assailants who laid in wait Sunday to attack men who had allgedly threatened them, the government news agency Notimex reported Monday.

However, the officers — two of who have been arrested, while three others fled — opened fire on the wrong vehicles, killing innocent partygoers, before realizing their error.

The seven dead included two children ages 7 and 12. Eight other people were injured.

The victims were traveling in a convoy of three trucks from the city of Nocupetaro (search) in central Michoacan (search) state before dawn when the assailants opened fire from the side of the highway with assault rifles, the state-run news agency Notimex reported.

Michoacan state Attorney General Angel Arellano Pulido (search) said the victims had nothing to do with the dispute. Arellano Pulido said the assailants appear to have been drinking, and that the alcohol — as well as the darkness — may have contributed to the error.

A spokeswoman for the Michoacan attorney general's office told The Associated Press she did not yet have official information on the attack.

The Milenio daily newspaper reported the intended victims were marijuana traffickers who allegedly had threatened police after they refused to provide them with protection.

The agency quoted a survivor of the attack as saying that one of the assailants screamed out "We made a mistake, these weren't the ones," before they fled.