Dozens of people were temporarily trapped Wednesday afternoon when a three-alarm fire tore through part of an office building in Mississauga.

The fire at 1270 Central Parkway West started around 5 p.m.

Shally Virk, who was on the third floor of the building when the fire broke out, said some of her co-workers began smelling smoke and "couldn't figure out where it was coming from."

Virk and about 10 of her co-workers then tried to exit the building by the stairs.

"Every exit we would go to there was smoke coming inside, it was black smoke," she said.

"So there was ... panic all over the office. Everyone [was] trying to figure out how to get out because there was absolutely no way to get out. We found an office in the corner of the building and we locked ourselves in there and put our coats underneath the door so the smoke wouldn't get in."

Two men tried unsuccessfully to break windows at the office.

"We were terrified," Virk said. "At that moment you actually do think: 'Oh my gosh, is this it?'"

Fire crews eventually arrived, broke down the windows and managed to get the office's occupants out.

Authorities gathered all the occupants of the building in buses and were making sure everyone is accounted for, Virk said.

It appeared no one was seriously injured. It was unclear how many people were trapped in the fire, although initial reports suggested up to a 100 people may have been affected.

Fire crews were still trying to put out the fire as of 6:45 p.m., although it appeared to be dying down, according to witness reports.