A stretch of Union Pacific Railroad near Medicine bow was shut down early Thursday after 21 cars from a train carrying mixed freight derailed.

Union Pacific Spokesperson Kristen M. South said via email that one line of track re-opened at 5:15 Friday morning while the second line is expected to re-open by the end of the day.

South said the derailment happened at roughly 3:30 a.m. Thursday when an eastbound Union Pacific train derailed near Medicine Bow.

No hazardous materials were spilled and no one was injured. Railroad officials continue to investigate the cause of the derailment.

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