The Office of the Fire Marshal is investigating the cause of a massive fire that ripped through a Mississauga factory this morning.

The fire broke out at a building on Wharton Way shortly before 2:30 a.m. and when crews arrived on scene, the structure was fully engulfed in flames.

Crews spent several hours trying to extinguish the stubborn fire, which caused significant damage to the building.

Reports from the scene indicate that the owner of the building, Maxxit‎ Systems, manufactures custom store fixtures and does architectural interior work for major North American retailers. There were a number of other tenants who reportedly leased office space in the building.

Employees were not working in the building when the fire started and no injuries were reported.

"We have a lot of projects on the go at the moment, a lot scheduled for the New Year. It was a very busy time and it is a very sad thing to see," Myles Davis, a project manager at Maxxit Systems, told CP24 at the scene.

"It couldn’t have happened at a worse time." 

He added that the company is a family-run business that started about eight years ago.

"They have been growing in size leaps and bounds over the past eight years," Davis said. 

"This is a huge blow."

Wharton Way north of Dundas Street was closed as firefighters attempted to knock down the blaze.

Mississauga Transit buses were brought in to shelter employees as they arrived for work.

"This building has collapsed down," Platoon Chief Gord Smith told CP24 at around 9 a.m.

"We are in the midst of getting heavy equipment here so we can start to pull some of the rubble off the top so we can get down to the scene of the fire."

The cause of the fire is not yet known.