A battle between two suspected Mexican gangs has left at least 20 bodies, 17 of them burned, in a town near the US border.
Mexican President Andres Manuel Lopez Obrador says initial information points to a battle between two groups, and security officials will give more details later.
A Mexican security official said 20 bodies were discovered on Wednesday, 17 of them burned, outside Ciudad Miguel Aleman in the state of Tamaulipas.
Five burned vehicles were also found near the bodies.
A separate state security official said on Thursday that 21 bodies had been found at the site.
The town is about 90kms from the Texas town of McAllen, where US Donald Trump is headed on Thursday to win support for his plan to build a wall between the US and Mexico.
He has threatened to declare a national emergency if Congress does not meet his demand for billions of dollars to build the wall.
Tamaulipas has become one of the most violent states in Mexico, convulsed by gangs fighting to control drug trafficking, extortion rackets and the exploitation of migrants.
Tens of thousands of people have been killed in the country during years of fighting between security forces and warring drug cartels.