Hamilton firefighters are attempting to douse a fire that has broken out at the Ancaster Aquatic Centre.

Fire crews were called at around 2:40 p.m. to investigate reports of heavy smoke.

Fire official Dave Christopher says a transformer in the Aquatic Centre and a transformer in the adjacent Ancaster High School both caught fire.

Both venues were empty and there were no injuries, he said.

Firefighters are "encountering heavy black smoke coming from the hydro vaults," so it may take a few hours to extinguish the flames, he said.

Christopher says it's too early to speculate on a damage estimate or cause of the fire.