BAY ST. LOUIS - Authorities have identified the truck driver whose 18-wheeler plunged into the Pearl River near the Mississippi-Louisiana state line following an accident on Interstate 10.

Louisiana State Police say the victim was 26-year-old Steven Shawn Clark, of Theodore, Alabama.

Troopers say the accident late Tuesday involved Clark's rig, another 18-wheeler and a third vehicle. Police are searching for the third vehicle believed to be a black truck.

Authorities say the pickup truck tried to pass an 18-wheeler driven by 45-year-old Andrew Chapple, of San Antonio, Texas, on the right shoulder. The truck hit the front of Chapple's 18-wheeler, which forced Chapple into the left lane where he collided with Clark's vehicle.

Clark's 18-wheeler was then pushed over the bridge barrier.

Clark was pronounced dead by the St. Tammany Parish Coroner's Office.