Poor weather conditions resulted in an almost 70-car pileup on I-64 in Virginia.

The crash happened on Sunday morning, The Virginian Pilot reports. Fifty-one people that were involved in the accident were subsequently taken to hospitals. Of those injuries, 11 were thought to be serious and two were life-threatening. The remainder of the injuries were minor.

The total count of cars involved in the crash was 69. During a news conference on Sunday afternoon, Virginia State Police spokeswoman Sgt. Michelle Anaya said that fog and icy roads were factors in the accident, but “the initial cause of the accident is still unknown.” There was also an eight-car crash on the same highway, Anaya said.

The number of vehicles has made the accident tough to investigate, according to Anaya. She said it could take days before the investigation is finished.

The part of I-64 where the crash took place is also a construction area where workers are trying to widen the interstate. A contractor said the crash didn’t injure the bridge.

At first, the number of vehicles that authorities thought were involved in the crash was 35, but that soon grew to 45, then 63, and finally 69. The number of injuries increased too, with reports saying there were 35 people treated, before tallying the final count of 51.

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