The gridlock of container ships outside the Ports of Los Angeles and Long Beach may have been the cause of a major oil spill off the coast of Orange County, California, according to authorities. 

As officials scramble to contain the damage done by a broken underwater pipeline that has sent oil onto beaches and endangered wildlife, they are also investigating the possibility that the leak was caused by a ship's anchor hitting the pipeline, CNN reported.

The Department of Transportation, which oversees pipeline accidents, notified pipeline owner Amplify Energy on Tuesday that while "the root cause of the accident remains unconfirmed at this time," that "preliminary reports indicate that the failure may have been caused by an anchor that hooked the pipeline, causing a partial tear."

"The pipeline has essentially been pulled like a bow string," said Amplify CEO Martyn Willsher.

The waters off the two busiest U.S. ports are clogged with an unprecedented number of container ships that have dropped their anchors as they wait to berth. As of late last week, when the accident appears to have happened, 64 container ships were waiting off the coast.

Even with the congestion, the ships should have been able to avoid the pipeline, according to the U.S. Coast Guard. Pipelines are clearly indicated on nautical maps, and ships should only drop anchors in designated areas.