A fire at a Department of National Defence building in Gatineau Thursday morning caused part of the building's roof to collapse.

One firefighter suffered minor injuries after the fire broke out at around 6:50 a.m. on the sixth floor of the Louis St. Laurent building at 555 Carrière Blvd.

The building was evacuated and no one working there was injured, according to a spokesperson from Public Services and Procurement Canada.

Police cordoned off the Louis St. Laurent building in Gatineau Thursday morning after a fire broke out on the building's sixth floor. (Jean-Sébastien Marier/CBC) Firefighters encountered heavy smoke but were able to bring the fire under control, said Gary Barnes, division chief of operations for the Gatineau Fire Service.

6th floor had been undergoing renovations

The fire caused a seven-by-three metre section of the roof to collapse into the top floor.

Firefighters also had to smash several of the top floor windows to clear the smoke from the building.

Gary Barnes, division chief of operations for the Gatineau Fire Service. (CBC ) The sixth floor had been undergoing a renovation, firefighters said.

Building engineers are on site to determine the stability of the structure before allowing firefighters to enter and investigate the cause of the blaze.

A portion of Carrière Boulevard was closed to traffic, as was the city's Rapi-bus service, resulting in traffic slowdowns.

The building will remain closed until further notice.

The Department of National Defence has put in place measures to ensure the department's work can continue. About 1,800 people work in the building.