A Red Hill pre-school has been evacuated after workers struck a pipe, causing a gas leak outside the building.

ACT Fire and Rescue were called to isolate the gas leak outside the French Australian Pre-School on Astrolabe Street, caused by workmen using a digger.

Sixty three people were evacuated from the building as a precaution. Two fire pumpers, HAZMAT and a command officer responded to the call.

Staff and students were to be allowed back in to the building shortly after 12.30pm.