It's a wonder no one was killed, although 5 of the 9 people taken to area hospitals were considered in serious condition.

Around 6:20pm on Saturday, multiple crashes occurred about 7 miles East of Pendleton on Interstate 84.

Authorities say a combination of black ice, snow and speed caused 20 vehicle to end up tangled in a pile of wreckage that stretched for hundreds of yards. The wreck resulted in a closure of the Interstate westbound between Pendleton and Ontario. 7 of the 20 were commercial semi-trucks.

It reopened Sunday, but it will be some time before authorities are able to piece together what triggered the initial wreck and subsequent accidents. 9 people were taken to a variety of hospitals including Tri-Cities, some by airlift, 5 of them are still in serious condition. For that reason, no names have been released.

The investigation continues. These photos show some of the damage that occurred.