SAN FRANCISCO -- A container ship traveling through dense fog bumped into a tower supporting the San Francisco-Oakland Bay Bridge on Wednesday morning, spilling thousands of gallons of oil into the water.

The accident caused no structural damage to the span, officials said, but the ship's hull suffered a large gash that poured about 58,000 gallons of fuel in the bay. The leak prompted the closures of five San Francisco beaches -- Fort Point, Kirby Cove, Baker Beach, China Beach and Crissy Field -- while authorities worked to clean up the oil, the Coast Guard said.

Several people who were at the Port of San Francisco reported getting headaches and feeling nauseated from inhaling oil fumes, but the city's public health department said no one was at risk from long-term health effects.

Hanjin Shipping's Cosco Busan ship, which was heading from Oakland to South Korea, struck a tower west of Yerba Buena Island around 8:30 a.m. The ship later anchored north of Treasure Island, outside the channel.

A veteran bay pilot was at the helm of the massive ship, guiding it out of the Bay at the time of the collision. Bay Pilot Association spokesman Peter McIssac said the collision left the ship with "extensive damage." He told KTVU the foggy conditions may have been a factor in the accident.

A team of California Department of Transportation (Caltrans) engineers examined the Delta Tower -- the third tower east of the San Francisco anchorage -- for damage. Caltrans spokesman Bart Ney said the bridge itself was not damaged but a massive steel fender system protecting it would have to be replaced.

"The vessel did not actually contact the bridge," he said. "We have a fender system that is on the outside of the bridge that acts as a bumper…It served its purpose…We lost about 100 feet of the fender system in the collision. There are several beams that are 8x10x14 feet and weigh 400 pounds apiece that have to be replaced."

Coast Guard pollution and marine inspectors conducted investigations into the cause of the accident, while an Army Corps of Engineers crew collected large wooden chunks from the bridge fender system that broke off into the water.

Traffic on the bridge was not affected by the incident.

Hanjin Shipping will pay for the cost of the bay clean-up. The process could take as long as a full month.

The port is posting signs warning people not to fish in certain areas near the spill. The Bay Area Air Quality Management Board is monitoring safety and will sample the air along the port property.

San Francisco police and the Coast Guard also enforced a 100-foot safety zone around the leaked fuel and the ship, docked north of Treasure Island, according to the Coast Guard.

The public is asked to report any injured or oiled wildlife to the Oiled Wildlife Reporting Hotline at (877) 823-6926.