A pipeline failure off the coast of Orange County, California, Saturday caused at least 126,000 gallons of oil to spill into the Pacific Ocean, creating a 33-square-kilometer slick that continued to grow Sunday, officials said.

Dead fish and birds washed ashore in some places as cleanup crews raced to try to contain the spill, which created a slick that extended from Huntington Beach to Newport Beach.

It was not immediately clear what caused the leak, which officials said occurred about 5 km off the coast of Newport Beach and involved a failure in a 28-km pipeline connected to an offshore oil platform called Elly that is operated by Beta Offshore.