Senior Patrol Agent Luis Aguilar was trying to stop a suspected smuggler who had illegally entered the country from Mexico when he was hit, according to Agent Michael Bernacke, a spokesman for the agency's Yuma sector.
The incident happened in the Imperial Sand Dunes Recreation Area about 20 miles west of Yuma at about 9 a.m. Saturday.
Bernacke said Aguilar was trying to place spike strips in the path of a Hummer and a Ford pickup truck on Interstate 8 when the suspected smuggler's vehicle hit and killed him.
Both vehicles fled into Mexico.
The FBI is leading the investigation, along with other federal, state and local authorities. Bernacke said Mexican authorities also have been contacted and that they are lending their full support to capture those involved.
"Today we mourn the loss of one of our own," Border Patrol Chief David Aguilar said in a statement. "This serves as a tragic reminder of the dangers our agents face every day while securing our nation's border and our way of life."
Bernacke said Aguilar was from El Paso, Texas and lived in Yuma with his family.
After a phone call was placed to Aguilar's home, family members declined to comment through a man who identified himself only as Border Patrol Agent Ruiz.
"They're still not strong enough to make any comments," Ruiz said. "He (Aguilar) was a terrific guy and everyone here took a big loss. We're all trying to cope, especially the family. We're trying to be as supportive as we can, and be here for them."
The Imperial Sand Dunes are the largest dunes in California, extending north of the border for 40 miles and averaging five miles wide.
The area is popular with off-road vehicle enthusiasts but also is frequently used by smugglers trying to bring people or drugs into the country from Mexico.