LONDON, ONT. -- London fire crews were kept busy battling a house fire in the SoHo neighbourhood Thursday.

Emergency crews were notified about the fire at 71 Adelaide St. North just before 11:30 a.m. Thursday after heavy smoke was seen billowing out of the back of the house.

There are no injuries but there is extensive damage to one of the apartment units. All tenants managed to get out safely but a secondary search for occupants took place.

Platoon Chief Gary Mossburger tells CTV News that it was a challenging fire to extinguish.

The cause of the fire isn't known yet and there is no damage estimate.