The Mexican government called for an investigation Friday into a shooting by two federal agents that left one person dead at the world's busiest border crossing. A union representing the Border Patrol agent involved in the shooting defended the officer's conduct.

The shooting took place Thursday afternoon after U.S. agents surrounded a sport utility vehicle that was under surveillance on suspicion of immigrant smuggling, police said.

The driver refused to get out, and when agents smashed the vehicle's window with a baton, he accelerated in the direction of five U.S. agents blocking his path and "nearly pinned an agent standing next to the vehicle," said San Diego police Lt. Jeff Sferra.

A Border Patrol agent and a U.S. customs agent opened fire. The Border Patrol agent's shots proved fatal, police said. The driver, identified by the Mexican Consulate as Oscar Abraham Garcia, 22, of Tijuana, Mexico, was pronounced dead at the scene.

Investigators have not said whether the driver was armed.

The shooting took place on Interstate 5, about 75 feet north of the Mexican border, at the crossing that links San Diego with Tijuana. The crossing was shut down for nine hours while the shooting was investigated.

Five male passengers, all illegal Mexican immigrants, were taken into custody. Some of the passengers told investigators that Garcia and a 17-year-old boy in the vehicle were both immigrant smugglers, said Alberto Lozano, spokesman for the Mexican Consulate in San Diego. Police said one person had been arrested on immigrant-smuggling charges.

At the time, the vehicle was going toward the Mexico border, not away from it, police said. Investigators had no immediate explanation for that.

"We asked for an official investigation of what happened," Lozano said. "We want to know why they shot this person."

Chris Bauder, president of National Border Patrol Council Local 1613, which represents Border Patrol agents in San Diego, including the one involved in shooting, said the agent followed his training.

"Based on what I've heard, it sounds like they acted properly and did what they do were trained to do. The suspect drove right at the inspector and posed a direct threat. His life was in danger," Bauder said.

Bauder said he did not know the status of the Border Patrol agent involved in the shooting, but noted that it is customary to be assigned to administrative duties pending the outcome of an internal investigation.

The American Federation of Government Employees used the shooting to call for improved benefits for U.S. customs agents.

U.S. Customs and Border Protection agents began following the SUV after somebody reported seeing it pick up suspected illegal immigrants on the U.S. side of another border crossing nearby, said San Diego police Lt. Kevin Rooney.