Was a UFO shot down during the "Battle of Los Angeles" in 1942?

On Wednesday, February 25, 1942, radar in Santa Monica picked up an "unidentified aerial object." At approximately 2:20 a.m., coast artillery batteries opened up, firing hundreds of shells. A photograph in the LA Times shows something that looks like a big triangular silver object pinned in searchlight beams. Did the 78th Coast Artillery shoot down a UFO that night? Was it a Japanese blimp or zeppelin? This was a real event--but what was it that was tracked and fired at for over four hours?