One worker died and another was missing Thursday after a column under construction collapsed on a newly opened bridge, sending nine workers plunging into the Bay of St. Louis, officials said.

Eight workers were taken to area hospitals following the accident on the U.S. 90 bridge, a two-mile span that partially opened to traffic last month. One of those workers later died, said George Mixon, Harrison County’s fire marshal.

Five of the workers were taken to Memorial Hospital at Gulfport, where Alger Pennamn, 51, from Jackson, was pronounced dead shortly after arrival, said Harrison County Coroner Gary Hargrove. Hargrove said the cause of death would likely be drowning, pending results of an autopsy.

The four other workers at Memorial were listed in stable condition, said Ginger Worth, a hospital spokeswoman. She would not release the names.

Three workers at Hancock Medical Center in Bay St. Louis were listed in stable condition, said Mary Harris, co-manager of the Hancock emergency room. She would not release their names.

One of the nine workers who fell into the water was still missing several hours after the accident, said Bay St. Louis Assistant Fire Chief Louis Prendergast.

Mixon said rescue workers suspect the missing worker was trapped under debris in the water.

The Coast Guard dispatched two rescue helicopters and a 25-foot boat to join the search, said Petty Officer Tom Atkeson.

The workers involved in the accident were employed by Granite Archer Western, the contractor in charge of building the new bridge. Company spokesman Dan Galvin wouldn’t release any additional information about the missing or injured workers.

“Until we finish investigating what happened, we have no further comment,” he said.

Workers were pouring concrete on the north side of the bridge when a column form failed and fell, according to Lisa Siegel, a spokeswoman for the Mississippi Department of Transportation.

“The whole column went into the water,” she said.

The bridge was temporarily closed to traffic after the accident, which was reported around 1 p.m. It later reopened.

“The structure is sound and it’s safe,” Siegel added.

Two of the bridge’s four lanes opened on May 17, replacing a bridge that Hurricane Katrina destroyed in August 2005. The $267 million bridge, which connects Bay St. Louis with Pass Christian to the east, is scheduled to be completed in November.

The new bridge is about twice as wide as the bridge that Katrina destroyed and is higher above the water — 30 feet at its lowest point and 85 feet at its highest point.