A massive gunbattle between rival drug- and migrant-trafficking gangs southwest of Nogales, Sonora, on Thursday afternoon left at least 21 people dead and six others wounded, prosecutors said.
The firefight occurred in a sparsely populated area about 12 miles from the Arizona border, which is considered a prime corridor for immigrant and drug smuggling.
The Sonora state Attorney General's Office said in a statement that nine people were captured by police at the scene of the shootings, six of whom had been wounded in the firefight. Eight vehicles and seven weapons also were seized.
Other media reports in Mexico put the death toll from the shooting and apparently related slayings that followed the shootout at 29. Reports said the Sinaloa cartel and the Beltran Leyva cartel were involved.
All of the victims were believed to be members of rival gangs.
The shootings occurred near a dirt road between the hamlets of Tubutama and Saric, in an area often used by traffickers.
Santa Cruz County Sheriff Tony Estrada said Thursday night that he was aware of the incident and his department was monitoring the situation.
Gangs often fight for control of trafficking routes and sometimes steal "shipments" of U.S.-bound migrants from each other, but seldom have they staged such mass gunbattles.
More than 23,000 people have been killed in drug violence in Mexico since late 2006, when President Felipe Calderón began deploying thousands of troops and federal police to drug hot spots.
Star reporter Jamar Younger contributed to this story.