That last explosion was the engine.
5 seconds sound clip from the The Thing from Another World movie soundboard.
You can hear this line at 00:23:14 in the Blu-ray version of the movie.
Quote context
[...]
- Wait a minute, everybody. Stay back.
- It's burning under the ice. Careful, captain.
- What's happening? Tell me, doctor!
- Get down on the ground, everybody!
- That last explosion was the engine.
- Sergeant, will you try your Geiger counter?
- It's all gone. Secrets that might've given us a new science... Gone.
- That's just dandy. Standard Operating Procedure. Ha!
[...]