Put it at the exact turning point where a calm setup becomes a crisis, then follow the reveal with Dramatic Dun Dun Dun to underline the bad news. For a physical gag, add Metal Pipe Clang just after the impact lands, keeping the alarm as the opening signal rather than the payoff.
About this sound
This 4.5-second clip is a repeating two-tone klaxon, rising and falling in a steady warning pattern with no voice or music. It feels tense and urgent, turning a calm scene into one where danger feels close and immediate. It comes from Star Trek, where the sound called the crew of the Enterprise to battle stations during an attack or serious emergency.