Northbound lanes of I-35W were shut down in Denton at FM 2449 Wednesday afternoon.
Ryan Grelle with the Denton Police Department says a portable building that was being transported on the road flew off and hit a pick-up truck.
All lanes of the freeway northbound were shut down, and police requested that Denton County officials shut down the freeway as far back as Argyle to help divert traffic during the shut down Wednesday afternoon.
At the location, there were no service roads to allow traffic to exit and officials recommended traffic through the area should exit early to get around the backup.
Police say there were no injuries.