Railroad crews were working Tuesday morning to clear a Union Pacific line between Hudson and West Lakeland Township in Minnesota after a multi-car derailment.

The derailment occurred on the Minnesota side, where a freight car could be seen tipped over, with a portion resting on a beach. Union Pacific Railroad spokeswoman Calli Hite said a total of seven empty cars derailed during the incident, which occurred at about 2 a.m. Tuesday.

She said the train crew reported debris on the tracks before the derailment occurred.

No one was injured in the incident and no hazardous materials were involved, Hite said.

The train, bound for St. Paul from Altoona, Wis., was carrying mixed freight, according to the company.

Hite said the cause of the derailment remains under investigation.

The company expected the track to reopen by Wednesday.