RIO BRAVO — Assailants wielding automatic weapons on Thursday shot and killed the former mayor of a Mexican border city and five companions outside a restaurant, local media reported.

Juan Guajardo, a career politician and the former mayor of the Rio Bravo, a city across the Texas border from Mercedes, was arriving at a restaurant in downtown Rio Bravo when the gunmen opened fire, killing him, his brother, two bodyguards, his driver and an unidentified man, the government news agency Notimex reported.

Officials at the attorney general's office in Tamaulipas state, where Rio Bravo is located, did not return calls.

Notimex reported that Guajardo, who was Rio Bravo's mayor during two terms and lost a re-election bid this year, was attacked earlier this year by gunmen who he told federal authorities were part of the Zetas, a group of Gulf cartel enforcers that includes former soldiers.

Tamaulipas state, on the border with Texas, has been plagued by drug-related killings. The state is the home base for the Gulf cartel.