DULUTH (AP) -- The largest freighter on the Great Lakes was stuck for about three hours after it ran aground near Bayfront Park in Duluth.

The 1,000-foot Paul R. Tregurtha reportedly got stuck near shore shortly before 4 p.m. Saturday.

Two tug boats helped free the ship at about 7 p.m.

A spokesperson for the Duluth Seaway Port Authority says the Tregurtha is an Interlake Steamship laker.

DuluthBoats.com says it's the largest freighter on the Great Lakes and was for a load at Midwest Energy in Superior, Wisconsin.

The cause of the grounding was not immediately known. There were no reports of injuries and no signs of pollution.