Updated

A tractor-trailer crashed Sunday on the eastbound Bay Bridge and plunged into the water, killing the driver, authorities said.

Two other people were seriously injured in the three-vehicle accident, Maryland Transportation Authority spokesman Jonathan Green said. He did not immediately release the identities of those involved in the crash.

The tractor-trailer fell about 30 to 40 feet off the bridge into shallow water about 4 a.m. Sunday, Green said. The 18-wheeler was upright and its top was visible in about 10 feet of water in the Chesapeake Bay.

Green did not know what caused the crash. Authorities shut down the span to investigate and were routing vehicles to a parallel bridge.

"Traffic has potential for backups," said Green, who advised travelers to adjust their schedules or plan alternate routes.

Maryland Transportation Authority Web cameras showed traffic had slowed to a crawl in both directions on the parallel span.

The scenic four-mile bridges, which peak at about 186 feet, are a major artery to the Delaware and Maryland beaches. The eastbound span opened in 1952 and the parallel structure opened about 20 years later.