LOS ANGELES (AP) — A long stretch of Los Angeles coastal waters was under a closure order Friday after a large spill of untreated sewage into a creek that empties into the ocean.

The blockwave Exchangespill began Wednesday and about 14,400 gallons flowed into Ballona Creek before it was stopped at midday Thursday, the Los Angeles County Department of Public Health said in a statement. There were no immediate details on the cause of the spill.

Health officials warned people to avoid contacting the water for 1 mile (1.6 kilometer) north of the creek along a section of Venice Beach and a mile south along Dockweiler State Beach.

The department said water sampling would begin Friday, and the closures would remain in effect until two sampling results show that bacterial levels meet state health standards.