A grenade attack on state government offices in Ciudad Victoria, the capital of the northeastern Mexican state of Tamaulipas, wounded at least two people, officials said.
The assailants threw two hand grenades at the state office complex on Tuesday afternoon, targeting the employees of the various agencies based in the facility, a spokesman for the Tamaulipas Attorney General's Office said.
Paramedics treated the wounded for cuts caused by shrapnel from the grenades.
State police officers, army troops and Federal Police officers cordoned off the area, while a helicopter monitored the complex.
The four-story Government Palace was evacuated following the attack.
The Gulf and Los Zetas drug cartels have been fighting for control of Nuevo Laredo and smuggling routes into the United States.
After several years as the armed wing of the Gulf cartel, Los Zetas, originally a band of Mexican special forces deserters, went into the drug business on their own account and now control several lucrative territories.
The war on drugs launched by former President Felipe Calderon, who was in office from 2006 to 2012, left about 70,000 people dead in Mexico, the government said.
A total of 1,104 people died in violent incidents in Mexico in January, the government said in a report earlier this month.
Of the 1,104 people who died in January in incidents linked to drug cartels and other organized crime groups, 1,068 were suspected criminals and 30 were police officers, soldiers and other public officials "who fell in the line of duty," the report said.
Mexican press tallies estimated that about 12,000 people died in violent incidents linked to organized crime groups in 2012. EFE