It seems to be the children.
4 seconds sound clip from the Chitty Chitty Bang Bang (1968) movie soundboard.
You can hear this line at 01:42:03 in the Blu-ray version of the movie.
Quote context
[...]
- Pardon me, sir. The castle? Le chateau?
- It seems to be the children.
- What's the matter with them? Haven't they seen children before?
- Haven't you noticed? There aren't any children. Not one.
- What's going on? What's happening? What's... Hey, you. What's happening? What's going on?
[...]