Sourcing status: Disputed — this is a contested claim, not independently verified. Presented as a documented claim, not established fact.
Anti-aircraft batteries fired roughly 1,400 rounds at one or more unidentified objects over Los Angeles in the early hours of February 25, 1942. The Office of the Secretary of War later concluded the engagement was triggered by weather balloons and war nerves; the Los Angeles Times front-page photograph of the searchlit object remains an iconic image.
Sources
primary_doc: Office of the Chief of Military History. Los Angeles Air Attack Report (1942)