No serious injuries were reported following a five-alarm fire at a commercial building in Wexford this morning.

The fire broke out at a mixed-use commercial building on Crockford Boulevard, near Warden and Lawrence avenues, shortly before 2:30 a.m.

Toronto Fire Capt. Ratushniak said the fire reportedly started in a front office and when firefighters arrived on scene, they spotted flames and heavy, black smoke coming from the building.

The fire grew and crews began a defensive attack from the exterior. At one point, the fire went through the roof.

Eventually crews were able to knock down the fire but firefighters remained on scene to battle hotspots.

No one was in the building when the fire started but one firefighter sustained minor injuries to his hand.

The cause of the fire is not yet known but investigators with Toronto Fire Services are on scene.

"We are currently in the preliminary stages of the investigation, conducting witness interviews," Division Chief Larry Cocco told CP24 at the scene.

"It is not safe to enter at this time. We have to assess some structural concerns."