A U.S. border agent has died following what government officials described as an attack in West Texas on Sunday morning that left a second agent seriously injured.

Rogelio Martinez, 36, was on patrol near Van Horn, Texas, roughly 90 miles east of El Paso, when his partner reported that they were injured and in need of assistance, according to a statement released by U.S. Customs and Border Protection.

Both agents were transported to a local hospital where Martinez died from his injuries. His partner, who was not identified, remains hospitalized, the CBP stated.

Texas Gov. Greg Abbott on Monday announced a reward of up to $20,000 for information leading to arrest of those responsible for the agents death.