The incident broke out in Ciudad Juarez, Mexico, just 30 yards from the U.S. border at El Paso, Texas, causing U.S. authorities to block off a portion of the city, CNN said Sunday.
Border agents reported gunshots about 9 p.m. EST near the University of Texas.
"The gun battle is still going on right now," U.S. Border Patrol spokesman Ramiro Cordero told CNN about 30 minutes after the incident began. The firefight occurred just south of the University of Texas in El Paso.
Details of the incident were not available, but a section of Paisano Street, which runs parallel to the Rio Grande River, was blocked for a time.