STAFFORD, Va. | A bus struck six vehicles on Interstate 95 in Virginia as traffic slowed for a work zone, killing five people and sending 34 to hospitals, state police said Friday.

The crash happened at about 2:35 a.m. on southbound I-95 in Stafford County. All five of the people who died were in vehicles hit by the bus, and three of the injured are in critical condition, police said.

“The preliminary investigation indicates that traffic was slowing southbound for an upcoming work zone,” state police said in a news release. “A bus failed to slow for traffic and struck six vehicles.”

It was not immediately known what the bus was being used for or how many people were aboard.

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The crash is under investigation and charges are pending, police said.

Southbound lanes remained closed seven hours after the crash, with traffic being detoured.

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