A barge carrying fuel drifted away from the tugboat pulling it and crashed into a bridge near Galveston, Texas, causing the span to partially collapse and cutting off the only road to a small island, officials said.
The vessel slammed into a pillar supporting the Pelican Island Causeway span on Wednesday morning (Thursday NZ time).
Video shows splotches of oil that spilled from the barge into Galveston Bay after the crash.
The barge, owned by Martin Petroleum, was able to carry up to 30,000 gallons, but the size of the leak is unclear.
The US Coast Guard said it had deployed a boom, or barrier, to contain the source of the spill and was using drones and personnel to determine how much oil was in the water.
The bridge, which provides the only road access between Galveston and Pelican Island, remained closed to incoming traffic, but vehicles leaving Pelican Island and pedestrians in both directions are unaffected.
Texas A&M University at Galveston, which has a campus on Pelican Island, urged staff and faculty to leave and said it was closing the campus, although essential personnel would remain.
“Given the rapidly changing conditions and uncertainty regarding the outage of the Pelican Island Bridge, the Galveston Campus administration will be relocating all Texas A&M Pelican Island residents,” through at least Sunday, it said in a statement late Wednesday.
Fewer than 200 people related to the school were on the island when the barge hit the bridge. Spokesperson Shantelle Patterson-Swanson said the university would provide transport and cover the housing costs of those who choose to leave, but underlined that the school has not issued a mandatory evacuation.
Aside from the environmental impact of the oil spill, the region is unlikely to see large economic disruption as a result of the accident, said Maria Burns, a maritime transportation expert at the University of Houston.
The affected area is miles from the Gulf Intracoastal Waterway, which sees frequent barge traffic, and the Houston Ship Channel, a large shipping channel for ocean-going vessels.
The accident came weeks after a cargo ship crashed into a support column of the Francis Key Bridge in Baltimore on March 26, killing six construction workers. - AP