The attorney-general’s office in Guanajuato, the violence-plagued state where Irapuato is located, said some 20 others were hospitalised with gunshot wounds.

Mexican President Claudia Sheinbaum said earlier yesterday that the victims included children, although the attorney-general’s office later confirmed only one casualty was a minor, aged 17.

“It is very unfortunate what happened. An investigation is underway,” Sheinbaum said.

Local media reported the shooting happened during an evening party celebrating a Catholic holiday, the Nativity of John the Baptist.

A video circulating on social media showed people dancing in the patio of a housing complex while a band played in the background, before gunfire erupted.

Reuters was not immediately able to verify the video.

Guanajuato has been for many years one of the most violent regions in the country.

On Tuesday, five other people were killed in other parts of the state, according to the attorney-general’s office.