Thirteen men and one woman were killed Sunday in the southern part of the state around the Gulf Coast port of Tampico and neighboring Ciudad Madero, with people shot on the street or at local businesses, according to a statement issued late that evening by Tamaulipas state's coordinating group of state and federal law enforcement.
The shootings were so widespread that some of the victims weren't found or reported until Monday. The bodies of three men killed in the Sunday shootouts were found Monday on streets in Tampico.
And in the border city of Ciudad Mier, near Roma, Texas, the bodies of three young men were found after they were shot to death Sunday near the banks of the Rio Grande, state officials reported Monday.
At least five other people have been killed in confrontations in the same region over the last few days: four suspected gang members who clashed with soldiers in the Miguel Aleman township on Saturday and a female mourner shot at a funeral in Matamoros on Thursday.
Tamaulipas is home to both the Gulf cartel and the Zetas drug gang. The confrontations followed joint operations by army and police that netted dozens of suspected drug cartel gunmen, along with vehicles and weapons.
The government statement did not identify the gangs involved in the Sunday clashes, but Tampico Mayor Gustavo Torres told Milenio TV that eight victims in his city were apparently linked to the Gulf Cartel.
On Saturday in Miguel Aleman, near Ciudad Mier, soldiers killed four gunmen, wounded two others and captured four after the army patrol came under fire from a sport utility vehicle that featured homemade armoring. Such vehicles are frequently used by area drug gangs and have steel plates welded across their windows and body panels. In and around the vehicle, soldiers found 17 rifles, including a .50-caliber sniper rifle, two grenade launchers and two grenades.
The previous day, gunmen had opened fire at a hotel in Ciudad Mier, but it was unclear whether anyone was hurt there. Eight employees of Weatherford International Ltd., a Swiss-based oil services company, were at the hotel, but all are "fine and accounted for," according to company spokeswoman Kelley Hughes.
Some clashes may have been sparked by raids during the last week of March, in which soldiers and police arrested 34 suspects, seized 41 vehicles, 28 guns, two grenades, marijuana, and thousands of rounds of ammunition and 1,677 gallons (6,350 liters) of stolen gasoline. Drug gangs in some parts of Mexico have made a side business of tapping into government-owned pipelines to steal fuel.
Confrontations can also erupt from inter-gang rivalries, which have raged in Tamaulipas for years.
On Thursday, gunmen opened fire on mourners in a funeral for two slain men in Matamoros, across the border from Brownsville, Texas, killing one woman.