The accident happened about 1 a.m. near Mission, Texas, along the border with Mexico, Customs and Border Patrol said in a statement. The agent was tracking a group of people who had crossed the border illegally.
The video above is ABC13's 24/7 Livestream.
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Fellow agents found the man unresponsive, began life-saving efforts and called for an ambulance, the statement said. The agent died at a hospital.
"The death of an Agent who died while securing our nation's border is a tremendous loss for our organization and our nation; our prayers are with his family and co-workers during this difficult time," said U.S. Border Patrol Chief Raul Ortiz in the statement.
The agency did not release the identity of the agent and declined further comment.
The Texas-Mexico border has seen multiple deadly accidents in recent years stemming from immigration-related pursuits.
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In June, four migrants died and three other people were injured after a Jeep being pursued by Border Patrol agents crashed into the back of a tractor-trailer on the interstate near the Texas border city of Encinal.
In January, Texas Department of Public Safety Special Agent Anthony Salas died after being involved in a single-vehicle traffic accident near Eagle Pass while working with U.S. Border Patrol to transport six people who had illegally immigrated to the U.S.
Last year, an Austin man was charged in the deaths of eight migrants after a deadly crash near the border city of Del Rio following a police chase.