(CNN) -- A tanker ship loaded with oil in the Port of Port Arthur, Texas, collided with two barges being towed by a tug boat, resulting in a spill of about 450,000 gallons of crude, according to the U.S. Coast Guard.
No injuries were reported, but a 50-block area around the port was evacuated out of caution, as the tanker was carrying a type of oil containing sulfide.
The portion of the port where the collision occurred will remain closed until it is deemed safe for workers and other vessels to return, Petty Officer Richard Brahm said.
The Coast Guard has deployed 4,000 feet of boom, which helps corral the oil, with 10,000 more feet available for cleanup. Also on the scene are oil skimmers, three boom vessels, four 25-foot Coast Guard boats, the Coast Guard cutter Manowar and authorities from the local police and fire departments.
The spill is in a "very still" area of the waterway, which is helping contain it, Brahm said.
"There is almost no water flow in the area, so the oil isn't spreading out," he said.
The port is primarily for industrial use, but Coast Guard Capt. John J. Plunkett said there are environmental concerns to marsh areas both up- and downstream of the spill. He said the spill hadn't reached those areas.
The Coast Guard did not indicate how long cleanup will take. The investigation into the cause of the collision is ongoing.
Port Arthur is about 100 miles east of Houston, near the Louisiana border.
The biggest oil spill in U.S. history occurred in 1989 when the Exxon Valdez ran aground on a reef in the Gulf of Alaska, resulting in the spill of 11 million gallons of crude.