Oily Substance on California Beach Prompts Officials to Close Coastline

— -- The entire Manhattan Beach coastline outside Los Angeles is still closed today after globs of an oily substance washed up onto its shores.

The tar-like material began appearing Wednesday afternoon and spread out across 6.5 miles of coastline, according to the U.S. Coast Guard. The source of the material is not yet known.

"We are continuing to analyze the beaches and try to determine the source of the tar balls and tar patties that washed up on shore yesterday," Charlene Downey, the on-scene coordinator for the U.S. Coast Guard, said during a news conference today.

Alexia Retallack, a spokesman for the California Department of Fish and Wildlife, told ABC News today, “We do have crews on scene.”

Officials have begun testing the substance to determine its source but do not expect the results to become available for at least a day. "It does take time to get those sent to the labs and analyzed so it could be a few days to a week," Downey said.

Officials have ruled out natural seepage as the source for the substance, saying the affected area doesn't match with known natural sources, according to Kenichi Haskett, an ocean lifeguard captain with the Los Angeles County Fire Department.

The Los Angeles County Department of Public Health posted closure signs along Manhattan Beach and residents have been urged to avoid the ocean.

The news comes a week after a Plains All American oil pipeline ruptured in Santa Barbara, dumping 101,000 gallons of crude oil onto the Refugio State Beach and leaving a 9-mile-long slick in the ocean that decimated sea life. Officials are still trying to clean up the Santa Barbara spill and have removed 10,000 gallons of oily water mixture.

It was not immediately clear whether the two events are linked.

In 2014, a permanent ban on drilling off the coast of Santa Barbara failed to pass the State Assembly. The bill's defeat marked a major success for Sunset Exploration and its partner Exxon Mobile, which are seeking to drill for oil on nearby Air Force property known as the Tranquillon Ridge.

Environmentalists have called on the State Assembly to reconsider the ban.