The U.S. Coast Guard, lead agency coordinating the cleanup effort, says six and half miles of beach have been affected.
"We have teams in the air, on the water, on the beaches conducting cleanup and surveillance of the areas from Redondo and Torrance Beach all the way to El Segundo," said U.S. Coast Guard Capt. Charlene Downey.
In a scene eerily reminiscent of last week in Santa Barbara County to the north, cleanup workers wearing white suits and gloves picked up tar balls on their hands and knees and deposited them in plastic bags.
Officials said 50 cleanup crews worked on the beach Thursday, and 30 more will join on Friday.
Teams working with city and federal agencies have collected samples of the water and of the substance in an effort to determine the source for the tar balls and tar patties.
The U.S. Coast Guard sent samples to a lab in Connecticut, and California Fish and Wildlife will be taking their samples and sending them to a lab in Sacramento.
But officials say it may take few days to a week to determine where the tar came from.
"It could be anything. It could be natural seep. It could be ships anchored. It could be ships transiting. It could be refinery. It could be any one of these possibilities," said Downey.
The U.S. Coast Guard is not ruling out any connections to the previous incident, but says at the moment the probability is not high.
"We have been in regular contact to with NOAA. The agency is analyzing the trajectory of the Manhattan beach tar and the Refugio Spill to see if there is any possible way this could have come from the Refugio Spill." said Petty Officer Michael Anderson.
Small bulldozers are collecting bags and driving past joggers and beachgoers to dump them into a disposable garbage container. The Coast Guard said 30 cubic feet of tar had been deposited into a dumpster so far.
Coast Guard confirmed to CNN that a citizen brought an oil-covered shore bird in a box.
Crews will be working second night in the row to continue the cleanup effort. There are no fresh tar balls being washed up ashore, according to Anderson.
The City of Manhattan Beach released a statement earlier today, saying the Los Angeles County Department of Public Health is hoping to open the beaches up at 6 a.m. Friday if there are no more tar balls or tar patties found in the water or on the beaches.