Those killed included town Mayor Conrado Mendoza and his father, the media said. (Representational)
A fight between two rival gangs in the violence-plagued southwestern state of Guerrero left 18 dead, including a mayor and a former mayor, and two more wounded, Mexican authorities said on Thursday.
Among those shot dead in San Miguel Totolapan on Wednesday were Mayor Conrado Mendoza, his father and former Mayor Juan Mendoza, as well as other local officials, according to a statement from the government of the state of Guerrero.
"It happened in the context of a dispute between criminal gangs," Deputy Security Minister Ricardo Mejia said, adding that organized crime groups La Familia Michoacana and Los Tequileros appeared to be involved.
Speaking at a news conference alongside President Andres Manuel Lopez Obrador, Mejia said an investigation was in course to find the perpetrators.
Investigators were also working to verify a video in which Los Tequileros appear to claim responsibility for the killings, he added. Both gangs are involved in drug smuggling, as well as extortion and kidnapping. Guerrero is an important heroin producing state.
Mexican daily El Universal reported earlier that the gunmen appeared to have carried out a coordinated series of attacks inside the building with the aim of killing the mayor.
Separately, in the central state of Morelos, state lawmaker Gabriela Marin was shot dead and her bodyguard wounded outside a pharmacy late on Wednesday. Mejia said that he "can't rule out revenge or another political motive."
Lopez Obrador's presidency has seen record levels of homicides.
He has been criticized by civil society for handing increased responsibility for domestic security to the armed forces, particularly through the creation of a National Guard that has been stacked with military personnel.
Originally intended to be a civilian institution - which replaced the Federal Police - the president has moved to place the National Guard under control of the Army.
The move received criticism by domestic adversaries and the United Nations over the militarization of public security and sparked protests across the country.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)