Almost 5,000 workers were evacuated from three buildings at Terrasses de la Chaudière in downtown Hull after a pipe carrying refrigerant gas burst early Tuesday morning.
Police said 10 Wellington St. and 1 Promenade du Portage would be reopened around 10 a.m. The offices at 25 Eddy St. were to remain closed for longer.
No one was injured in the blast.
Police said a maintenance worker accidentally caused the leak.