Scare the bejesus out of sb: to frighten, annoy, bore, etc. someone very much [Cambridge].
Scare the bejesus out of sb: To shock or frighten one very suddenly or severely. ("Bejesus," a mild euphemistic oath, is here used as an intensifying noun.) [Idioms Free Dictionary]
The sound of the fire alarm scared the bejesus out of us this morning.
For more information of bejesus (derived by "by Jesus") see here [ESE]
What are some common ways to express a similar idea in French?