MONTREAL: A small plane has crashed onto the roof of an office building near Toronto, killing the pilot and his passenger, police said.The single-engine Cirrus SR-20 crashed in Markham, Ontario following an explosion, according to witness reports in Canadian media. The police declined to elaborate on what damage was done to the building.The 14 employees of a toy company Thinkway Toys, were able to be evacuated, and two were injured, local media said.Authorities were investigating the cause of the crash.