A crane lifts pre-fabricated rail sections onto the track bed behind train car debris during the cleanup of Tuesday's Union Pacific derailment north of Twin Peaks Rd on July 11, 2018.

The second railroad track damaged during Tuesday's train derailment reopened for travel in Marana Thursday, a Union Pacific official said.

The massive derailment involved 27 freight cars on Tuesday afternoon and closed the Interstate 10 frontage road from Twin Peaks to Avra Valley roads.

Union Pacific crews had been working to clear equipment and make repairs to the track for operations to resume since Tuesday evening. The first track was reopened on Wednesday for trains to travel at reduced speeds.

The tracks are a main freight route between California and Texas, according to Union Pacific. 

Crews are still working to move contents onto rail cars or trucks to be transported out, which continues to shut down the I-10 frontage road. A time for reopening has not been determined.

On Tuesday, various items were displayed across the area, including UPS packages confirmed on board during the derailment.

No injuries were reported and no hazardous materials were involved, officials said.

Running water was on the tracks when firefighters arrived, said Brian Keeley, a Northwest Fire District spokesman, but the official cause of the derailment has not been released.

Contact Star reporter Shaq Davis at 573-4218 or sdavis@tucson.com

On Twitter: @ShaqDavis1