LIVE OAK SPRINGS, Calif. -- A U.S. Border Patrol agent opened fire on the occupants of a truck during a confrontation near an East County gambling hall Friday, seriously wounding at least one of them, authorities reported.

The officer-involved shooting on a roadside in front of Golden Acorn Casino in the rural Live Oak Springs area was reported about 11:30 a.m., sheriff's Lt. Mike Munsey said.

The chain of events leading to the gunfire began when plainclothes personnel with the federal agency began following the pickup near the U.S.-Mexico line, believing the vehicle might be connected to smuggling operations, Border Patrol public affairs Agent James Jacques told a local TV station.

The suspect driver pulled over alongside Old Highway 80, just south of Interstate 8 and Crestwood Road, but then accelerated the truck toward one of the agents as he approached on foot, prompting him to open fire, Jacques said.

Both occupants of the truck were wounded, at least one of them seriously, a local TV station reported. The suspects were taken to Sharp Memorial Hospital.

The federal officers were uninjured, according to Jacques.