A trail derailed northwest of Tucson Tuesday.

The incident happened between Twin Peaks and Avra Valley along I-10, according to the Northwest Fire District.

Northwest Fire District said the derailment happened due to the rain. Water was flowing over the tracks.

Over 20 cars were scattered near the highway.

Traffic is backed up on the I-10 northbound near the derailment.

Contents of the derailed cars appear to include cardboard boxes. There were no reports of hazardous materials aboard, but hazmat crews are doing a sweep.

Rain caused a train derailment northwest of Tucson July 10, 2018. (Photo: Northwest Fire District)
Rain caused a train derailment northwest of Tucson July 10, 2018. (Photo: Northwest Fire District)
Stegen, Anne