Gunfights and blockades of burning vehicles have been reported in the Mexican border city of Reynosa, across from McAllen, Texas.

The U.S. consulate in Matamoros said in message Friday that it had "learned of several firefights and roadblocks throughout the city of Reynosa," and it recommended that U.S. citizens take precautions.

The city government posted a warning on its Twitter site recommending motorists avoid several areas, including the highway to the nearby city of Matamoros.

A Mexican federal official who was not authorized to be quoted by name confirmed the burning of vehicles, roadblocks and shootouts. But he could not immediately confirm reports a top member of the Gulf drug cartel had been detained.

Warring factions of the Gulf cartel have been fighting turf battles around Reynosa and Matamoros.