The bodies were found Wednesday afternoon near four charred pickup trucks and a sedan in the rural community of Refugio Hinojosa near the town of Miguel Aleman, federal police said.
Several photos provided by police showed some remains next to the burned-out wreckage of the vehicles.
The incident appeared to be the result of a confrontation between two criminal gangs, Tamaulipas Attorney General Irving Barrios Mojica told journalist Carmen Aristegui in an interview for her radio show in Mexico. Aristegui is also the host of a show on CNN en Español.
He said some of the victims had been wearing "tactical vests with military-type uniforms" and bullets were found nearby that came from weapons typically only used by the military.
Barrios Mojica indicated the area where the bodies were found is being fought over by criminal gangs looking to traffic drugs, weapons and people.
CNN's Sebastian Espinosa contributed to this report.