A pipeline ruptured Tuesday in California dumping oil along the rocky coast of Santa Barbara and into the Pacific Ocean, the US Coast Guard said.
The oil pipeline runs along a coastal highway, and the leak sullied waters at a nearby beach, said Coast Guard Petty Officer Andrea Anderson.
Oil reached along about four miles (six kilometers) of beach, the Coast Guard said on Twitter.
The rocky coast line was colored black by layers of greasy oil and volunteers in rubber boots had mobilized to help in clean-up efforts.
The leak -- which began around midday --- affected a pipeline operated by Plains All America Pipeline, which stopped the flow of oil, the company said.
It said the oil reached the ocean through a drain which has now been blocked off, and "no additional oil is reaching the water."
Plains All America Pipeline said it does not know how much oil leaked.
"Plains deeply regrets this release has occurred and is making every effort to limit its environmental impact," the company said in an email.
Crews from state and federal emergency responders and oil companies were on the scene to begin the cleanup.
The spill was estimated at 21,000 gallons (80,000 liters) of oil, local media reported.