If you hear gun fire coming from Parliament Hill tonight, don't be alarmed.

Each year, the Ceremonial Guard hosts Fortissimo, described by the Federal Government as "a military and musical spectacular."

The event is a noisy affair with cannon and rifle fire (all shooting blanks) and flybys from a CH-146 Griffon helicopter and CC-177 Globemaster III aircraft.

The festivities run from 7 to 9 p.m. on Thursday, Friday and Saturday.