The government of Tamaulipas state said today that Humberto Loza Mendez died over the weekend in the clash.
Loza Mendez and his three companions were believed to be members of a faction of the Gulf cartel who were fighting turf battles with other factions.
Authorities had offered a reward of 2 million pesos (about USD 108,000) for Loza Mendez, who was also known as Steven and "Betillo."
The government said Loza Mendoza was one of the drug gang leaders who had caused much of the violence in Reynosa, which has been hit by running gun battles and street blockades.