Residents posted a flurry of videos on social media, together with theories of aliens or meteors. Others made panicked calls to law enforcement officials.
But not to worry, U.S. military officials said. It was a planned missile test.
The Navy Strategic Systems Programs held a scheduled missile test flight at sea from USS Kentucky, which is a ballistic missile submarine. The test was conducted off the coast of Southern California, the Pentagon said in a statement.
It said the missile was not armed.