There's the entrance.
2 seconds sound clip from the It Came from Outer Space movie soundboard.
You can hear this line at 01:16:54.660 in the Blu-ray version of the movie.
Quote context
[...]
- Free the girl first. Show the mob you mean them no harm.
- You can always reach out and destroy us with that.
- Clear away, everybody. Clear away. Keep running, Ellen.
- Hey. Hey. Any way to close off this entrance?
- There's some dynamite back there.
- Hurry up. We've got to keep that posse away from them.
- Yeah.
[...]