The Tamaulipas security spokesman's office says the men were killed in separate pre-dawn shootouts today.
One man was killed in the border city of Reynosa. He was tentatively identified as Julian Loisa Salinas, better known as "Comandante Toro." He reportedly led the Gulf cartel in Reynosa.
His supporters earlier had set fires and tried to block roads in Reynosa in an effort to help him escape.
The leader of the rival "Zetas" cartel in the Tamaulipas state capital of Ciudad Victoria was also killed. He was tentatively identified as Francisco "Pancho" Carreon.