The state prosecutor’s office said it was investigating the attack, while military and federal agents were deployed in the area.
Dozens of local officials in Mexico have been targeted by organised crime groups in recent years, especially in areas where powerful drug trafficking gangs operate.
The violence has recently spread to the capital, Mexico City, where two close associates of Mayor Clara Brugada were murdered a month ago in public.
Criminal violence, most of it linked to drug trafficking, has claimed about 480,000 lives in Mexico since 2006, with more than 120,000 people missing.
– Agence France-Presse