Canada ? One of Quebec’s most historic buildings collapsed in a massive fire that raged into Saturday morning, authorities said.

No injuries were reported at the Quebec City Armoury, which was built in 1884 and houses a Canadian Forces reserve unit.

Most of the building collapsed about two hours after the fire began, leaving only a brick wall and two towers standing at the main entrance.

Police said they did not know what caused the blaze.

Nobody was inside the building when the fire started, said Capt. Paul Sacca, a spokesman for the Canadian military. Witnesses said that after the fire broke out, an explosion was heard in the building.

The blaze had not been contained by early Saturday, Sacca said.

The building, which was being renovated, contains a museum and is famous for its suspended wood ceiling.

The building had been scheduled to host events for Quebec City’s 400th anniversary this year.