Records show the U.S. Coast Guard received a report of a possible Southern California oil spill more than 12 hours before a pipeline company reported it and the Coast Guard launched a cleanup effort.

State reports reviewed Monday by The Associated Press raise questions about the Coast Guard’s response time as well as how quickly Amplify Energy recognized it had a problem with its pipeline and notified authorities.

Officials say they’re investigating whether a ship’s anchor may have struck the pipeline on the ocean floor.

The spill sent over 572,000 litres of heavy crude into the ocean.

It contaminated the sands of Huntington Beach and other coastal communities.