West Grey Police and EMS have also responded.
The blaze is said to have started at around 2:30am.
The area around the building on 10th Street is closed.
Updates will be provided as they are made available.
HPS is on scene of a fully engulfed fire at Fabulous Fashions & the former Forum Hotel Rooming House. Fire crews from Hanover, Walkerton, West Grey and Elmwood continue to battle the blaze. We are asking everyone to avoid the Downtown Core. 10th Street is closed from 9th Ave to pic.twitter.com/fUmewc2Lu9
— Christopher Knoll (@ChiefKnoll) May 19, 2022