Eleven people, including two state police officers, have been killed in northeast Mexico along the Texas border, a state security official said Monday.
Tamaulipas state security spokeswoman Ivon Melendez said that nine suspected criminals were killed after attacking state police in the border town of Rio Bravo on Saturday afternoon. Rio Bravo lies in territory controlled by the Gulf drug cartel.
Police seized nine long guns and tactical equipment.
Also on Saturday, two off-duty state police officers were killed in the border city of Nuevo Laredo. Melendez said they were on their way to Laredo, Texas, to shop when gunmen in two vehicles opened fire. One officer survived the attack.
The Zetas cartel controls Nuevo Laredo.
Melendez speculated that the attack could have stemmed from weapons, drug or cash seizures by authorities.
She said she knew of no alert for law enforcement following the attack.