UPDATE (6:00 P.M.) - A Union official said the agent - Rogelio Martinez - appeared to have been struck in the head with a rock or rocks.The investigation into the incident continues.

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WESLACO – Federal authorities are investigating the death of a Border Patrol agent in West Texas.

The FBI is leading the investigation into the attack on two Border Patrol agents. The acting commissioner for Customs and Border Protection sent a letter to agents saying 36-year-old Rogelio Martinez was found with multiple injuries to his head and body.

Martinez was on a call with his partner early Sunday morning in the Big Bend sector near the Rio Grande River. They were on I-10 near Van Horn.

Investigators said his partner called for help saying they’d both been hurt. Both were rushed to a hospital. That’s where Martinez died and his unidentified partner is hospitalized in serious condition.

People who live in Van Horn said the Border Patrol presence is a big part of everyday life.

“We feel pretty protected here in this community. So to hear about something like an attack on officers, we want to make sure that we can do whatever we can to help,” resident Adrian Gilmore said.

According to CBP, Martinez was an El Paso native and a Border Patrol agent since 2013.

Border Patrol records show that the Big Bend sector accounts for only one percent of the apprehension made by agents along the southwest border.

The mountains and the river make it a difficult area for people trying to cross into the country illegally.

Thirty eight Border Patrol agents have died in the line of duty since 2003. Some attacked while working along the border, and others killed in traffic accidents.