More than 50 people were hospitalized after 69 cars collided in a chain-reaction crash on a Virginia interstate on Sunday morning, state authorities say.

Images from Interstate 64 in York County near Williamsburg showed cars and trucks strewn together in a tangled heap following the pileup.

Virginia State Police said the crashes began on an icy and fog-shrouded overpass bridge around 7:51 a.m.

"Fog and ice were causative factors, but the cause of the actual accident, we do not know at this time," said Virginia State Police spokeswoman Sgt. Michelle Anaya.

Traffic was shut down in both directions as rescue workers recovered the injured and cleared the scene. Lanes on the westbound side of the interstate where the crash occurred reopened roughly seven hours after the pileup. The eastbound side of the highway was closed for about three hours.

Local hospitals treated 51 patients as a result of the pileup, but nobody sustained life-threatening injuries, Anaya said.

Authorities have not reported any deaths.

Shaun Stewart, the owner of the Williamsburg Flight Center, flew a plane over the wreckage Sunday morning.

He said the fog was so thick, he had to wait more than an hour after the accident took place before it was clear enough to take off.

"It was a bit shocking to see how they were all so tightly packed together," Stewart said. "I have to imagine it was because of the heavy fog that was wafting all around this morning."

The National Weather Service reports that dense fog had reduced visibility to less than a quarter mile or less just before the incident.

Anaya said the investigation into the crash is ongoing. State officials are asking motorists to avoid the area.

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