HERMOSA BEACH (CBSLA.com) — A 7-mile stretch of South Bay shoreline were reopened Friday after crews cleaned up remaining tar balls that washed ashore, authorities said Friday.

The mysterious globs, which range in size from golf balls to softballs, were first reported along the 2200 block of The Strand just after 12:30 p.m. Wednesday.

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The shoreline from the El Segundo jetty to the Torrance/Redondo Beach border was closed as a precaution and were reopened Friday evening, a U.S. Coast Guard spokesman said.

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Authorities said cleanup crews will remain available to respond to the shoreline should they be needed.

Residents had been asked to avoid water contact from 34th Street in Manhattan Beach south to Longfellow Avenue in Hermosa Beach.

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(credit: CBS)

(credit: CBS)

The source of the substance has yet to be determined. Samples have been sent to two labs to be analyzed.