According to police, shooters opened fire on a group of students on Monday night, killing three males and two females aged between 16 and 18, as well as a 65-year-old woman who was in the same area.

“Unfortunately we can say that a few hours ago in the Barron community six people lost their lives in an armed attack,” said Cesar Prieto, mayor of the city in Guanajuato state.

The mass shooting happened just two weeks after eight women and three men were killed in an apparent gangland revenge attack on two bars and a hotel in Celaya, another city in Guanajuato.

Located in Mexico’s prosperous industrial centre and home to a refinery and a major pipeline, Guanajuato has become one of the most violent states in Mexico due to a dispute between the Santa Rosa de Lima and Jalisco New Generation cartels.

The gangs fight for control of trafficking routes for drugs and stolen fuel.

Since December 2006, when the government launched a controversial military anti-drug operation, Mexico has recorded more than 340,000 murders, according to official figures.

Authorities have blamed most of the killings on organised crime.