A 669-foot tank ship, flying under the Liberian Flag and carrying orange juice collided Thursday with a dredging vessel in Newark Bay, causing the spill of a small stream of hydraulic fluid and prompting authorities to shut down the harbor for several hours.

The collision happened around 1:50 p.m. near Port Newark, on the west side of a channel between Bayonne, N.J. and Newark, did not injured any of the 20 people on board, Petty Officer Third Class Annie Berlin said, according to Reuters.

Tugboats escorted tank ship, Orange Sun to Berth 24 at Port Newark. 200-foot dredging vessel, New York, was linked to a barge and tugboat after water was removed from the ship. The five people on board were evacuated and suffered no injuries.

The Melvin Lemmerhirt, a 117-foot dredging ship was also near the accident, but managed to get out of the way just before the collision, the Coast Guard said.

Investigators were trying to determine how the accident happened. The waterway was reopened yesterday about 7 p.m.

“A small amount of hydraulic oil from the New York leaked into the bay. There are no reports of major pollution,” Berlin said, according to the same source.

The New York was working on a $2.5 billion project to deepen New York Harbor and the surrounding channels to 50 feet, from 45 feet, to allow bigger container ships to dock in New York and New Jersey.

According to Hal Hawkins, the manager for the project with the Army Corps of Engineers, which is working on behalf of the Port Authority of New York and New Jersey, the New York is the largest excavator of its kind in the country.

The dredge is owned by Great Lakes Dredge & Dock Co. of Oak Brook, Ill. The company declined to comment on the event yesterday, when called.