The I-10 frontage road is closed between Twin Peaks and Avra Valley Road due to a train derailment on Tuesday.
Marana Police say to use alternate routes if possible.
The Arizona Department of Transportation says the area will be closed for 24-48 hours.
Union Pacific says that 27 cars derailed during this incident. There was a two-person crew on board that was in the front of the train. The train was carrying large shipping containers from Los Angeles and heading to Texas.
The cause of the derailment is still under investigation. Union Pacific says rain and flooding on Wednesday is being considered.