At least nine people died in shootouts involving rival drug gangs in Reynosa, a border city in the northeastern Mexican state of Tamaulipas, that prompted the army to intervene, a military spokesman said.
Drug cartel gunmen blocked a number of the main avenues in Reynosa, located across the border from McAllen, Texas, an 8th Military Zone spokesman said.
The first shootout started around 6:00 a.m. Saturday on the Monterrey-Reynosa highway near the entrance to the border city, leaving four men dead inside an SUV.
Gunmen then engaged army troops in the Villa Florida district of the city, the military spokesman said.
Shootouts between soldiers and gunmen occurred later in the Unidad Obrera, Granjas, Cumbres and Vista Hermosa neighborhoods, as well as in downtown Reynosa, leaving five gunmen dead, the military spokesman said.
All of those killed in the shootouts were suspected cartel members, the army said.
Gunmen blocked at least seven important avenues in the border city after the shootouts, causing chaos in the area.
Social-networking sites reported that the three international bridges were closed, but U.S. officials said the border crossings stayed open.
Reynosa is controlled by the Gulf cartel, which has been battling Los Zetas for smuggling routes in the area.
The army is carrying out "Operation Northeast" in the states of Nuevo Leon, Tamaulipas, Coahuila and San Luis Potosi against the drug cartels that operate in the region.
The Gulf drug cartel has been waging a war in northeastern Mexico against Los Zetas, a band of army special forces deserters turned hired guns and drug traffickers.
After several years as the armed wing of the Gulf cartel, Los Zetas went into the drug business on their own account and now control several lucrative territories.
More than 50,000 people, according to official figures, have died in drug-related violence in Mexico since late 2006, when President Felipe Calderon took office and declared war on the country's powerful drug cartels.
Calderon has deployed tens of thousands of soldiers and Federal Police officers across the country to combat drug cartels and other criminal organizations.
The use of the armed forces to fight drug traffickers, however, has failed to stem the violence.
Mexico registered 27,199 murders in 2011, or 24 per 100,000 people, the highest number since Calderon took office, the National Institute of Statistics and Geography, or INEGI, said in a report released on Aug. 20.
A total of 57,449 people have died in the war on drugs since Calderon took office on Dec. 1, 2006, a tally published Thursday by the Milenio newspaper shows. EFE