The Sir John Carling building, former headquarters of Agriculture Canada, came crashing down Sunday morning in a controlled explosion.

An Idaho-based company carried out the demolition around 7 a.m. ET, setting off 800 pounds (362 kilograms) of explosives that were packed inside the abandoned 11-storey structure.

Dozens of people gathered around the building as it was turned into 40,000 tonnes of rubble. Police enforced the perimeter of the site at 930 Carling Ave., to balance safety concerns with people's eagerness for a good view.

Lisa Kelly, part-owner of the company in charge of the blast, said the implosion went off perfectly.

The building housed Agriculture Canada employees since 1967, but was vacated in 2009.