Fire crews attend the scene of the plane crash on an office building in Markham, Ont. The plane smashed onto the roof of 8885 Woodbine Ave., the headquarters for Thinkway Toys. ((Muhammad Lila/CBC) )

A small plane crashed onto the roof of an office building Tuesday in Markham, north of Toronto, killing the two people on board.

The four-seater Cirrus SR-20 had taken off from Buttonville Airport just a few minutes before the crash, about a half-kilometre from the airport, at about 12:30 p.m. ET.

The names of the victims — the pilot of the aircraft and passenger — have not been released.

"[The plane] had just stopped down in Buttonville temporarily and had just taken off from Buttonville and was experiencing problems when it crashed," said Dennis Flaherty, a spokesman for the Town of Markham.

The plane normally flies out of Burlington, some 70 kilometres away, but was having work done on its radio. The pilot didn't file a flight plan because of the short distance, so officials did not immediately know who was on board, said Markham Mayor Frank Scarpitti.

Louise Lorenc, York EMS operation supervisor, said the crash scene had become a "recovery operation."

"There was a fairly large explosion," she said.

Witnesses said smoke was coming from the plane and that it rolled before it crashed onto the roof of the office building at 8885 Woodbine Ave., at Woodbine Avenue and Hooper Road.

The building is the headquarters for Thinkway Toys.

Firefighters were on the scene quickly, extinguishing a fire and evacuating workers from the building.

There were 14 people inside the building when the plane hit. Only two minor injuries were reported. 

Toy designer Anthony Vanbruggen, 48, said he was among the workers who escaped.

"As soon as we opened the door the roof was down, fuel or liquid of some sort was coming toward us, so we backed off," Vanbruggen said.

"There was no smoke but the fumes were crazy."

He described the explosion that followed the crash as a "little fireball."

The Transportation Safety Board has sent seven specialists to investigate the crash.

With files from The Canadian Press