A group of five gunmen sprayed three passenger buses with bullets in Mexico's Gulf coast state of Veracruz on Thursday, killing seven passengers, before being chased down and killed by soldiers.
Veracruz state government spokeswoman Gina Dominguez said the gunmen apparently resisted detention and died in the ensuing confrontation. They all had rifles and were traveling in a bulletproof vehicle.
While the attackers' identities and cartel affiliation have not yet been established, the men killed match witness descriptions of the assailants in the bus attacks, Dominguez said.
Earlier, gunmen killed four people in the town of El Higo in northern Veracruz, where drug gangs have been particularly active, but Dominguez said those killings appear not to have been related to the bus attacks.
The bloody pre-Christmas bus shootings brought up memories of the brutal murder of dozens of bus passengers whose bodies were found in mass graves in the neighboring state of Tamaulipas in April. A total of 193 bodies had been found in 26 graves, and officials say most of those were Mexican migrants heading to the United States who were kidnapped off buses and killed by the Zetas drug cartel.
But there appeared to be differences between Thursday's killings and the murders in Tamaulipas.
In the Tamaulipas killings, the Zetas gunmen stopped and boarded buses and removed male passengers and killed them, either because they believed a rival gang was trying to send reinforcements into the region aboard buses or because they wanted to force some of the passengers to join their gang.
Thursday's attacks on buses may have been more random; the gunmen apparently just sprayed passing buses with gunfire. The buses hit were covering local routes in northern Veracruz, though authorities did not release the names of the bus lines operating the route.
There was no immediate information on the identity of the dead bus passengers, or the four people killed in El Higo.
The area has been the scene of bloody battles between the Zetas and their former allies, the Gulf cartel.
The two gangs split in 2010.