Sixteen vehicles crashed in a pileup on the Interstate 70 flyover to Interstate 225 Thursday evening causing injuries to nine people.

Aurora police managed to keep one lane open as crews cleared the vehicles from the flyover and attempted to remove any ice and snow from the highway, a Colorado Department of Transportation spokesman said.

Lt. Rob McGregor said the flyover does tend to freeze up first because it’s elevated, and he described the stretch of highway as being icy and wet.

"It’s just the flyover that’s freezing over, and people are not using caution," McGregor said.

Traffic investigators were attempting to determine what triggered the pileup.