Prime Minister Robert Borden, who was in his office at the time, escaped down a back stairway. With World War I raging in Europe, rumours spread that the fire was caused by enemy sabotage, but a Royal Commission into the fire determined that the cause was accidental. Here's a summary of the Parliament Buildings fire and also a photo gallery of historic Pictures of the Parliament Buildings Fire.
More on Parliament in Canada
An Introduction to Parliament in Canada
Role of Canadian Members of Parliament
Role of Canadian Senators
Canadian Parliament Glossary