What happens if there is a short circuit in a parallel circuit?

Incorrect answer

Then only one of the lights go out.

Correct answer

Actually ALL the lamps will go out if a short circuit occurs across any branch of a parallel circuit because, if the wiring has been done correctly, a circuit breaker will trip or a fuse will blow to cut off the supply of current to all the lights.

The loss of a single lamp indicates a break, not a short circuit.