This was the first episode of the television show Dragnet, which originally aired December 14, 1951 when I was about to turn 8-years old. Via regular broadcast TV or via online streaming, I have probably seen every episode of Dragnet.
In it, Sergeant Joe Friday (Jack Webb), Sergeant Ben Romero (Barton Yarborough), and Chief of Detectives Thad Brown (Raymond Burr), confront a bomber in City Hall who wants to free his brother from jail.
The print is damaged, and the audio (at least to me) seems slightly out of sync, but the episode is intact. The missing audio during the end credits was solely due to a copyright notice