Nine suspected criminals and two soldiers were killed in a clash pitting Mexican army troops and gunmen in the northeastern border city of Matamoros, where numerous road blockades also were set up, officials told Efe.
A government spokesman in Tamaulipas state, where Matamoros is located, said the 11 deaths occurred during a chase and shootout on Friday.
That morning, numerous roadblocks were set up on the Matamoros-Reynoso highway and on streets and avenues in Matamoros and nearby towns, he said.
Gunmen removed people from cargo trucks and cars and used the vehicles to block main thoroughfares, causing traffic chaos and impeding the movement of security forces.
The spokesman said the most affected avenues were 12 de Marzo, Lauro Villar and Libramiento Emilio Portes Gil.
The U.S. Consulate in Matamoros gave updates in Spanish on the road blockades on Twitter, first saying reports indicated several roads had been blocked and later adding that all the roadblocks had reportedly been cleared.
The presence of federal forces has intensified this week in Matamoros, but authorities have not issued any official reports in that regard.
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.
More than 50,000 people, according to official figures, have died in cartel turf battles and security force operations in Mexico since late 2006, when President Felipe Calderon took office for a six-year term and militarized the struggle against the country's powerful drug mobs.
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.
The Movement for Peace with Justice and Dignity, which was founded by poet-turned-peace activist Javier Sicilia after his son was murdered last year by suspected drug-gang members, puts the death toll from Mexico's drug war at 70,000. EFE