NEWELLTON, N.S. -- Nova Scotia's Department of Labour has issued a stop-work order at a construction site in southwestern Nova Scotia after a roof collapsed, injuring several workers.

Chrissy Matheson, a spokeswoman for the department, says inspectors are investigating the site, but did not yet know what caused the roof to fall in Thursday at around 5:30 p.m.

Matheson says the section of the roof that collapsed was under construction on a partially built warehouse.

One of the workers was taken to hospital with serious injuries, while two others suffered minor injuries at the site near the wharf in Newellton, a small town on Cape Sable Island.

Matheson says construction can't resume on the site until there is an engineered plan to ensure the work is done safely.

A fire official said the man was rescued after firefighters spent 45 minutes cutting through wooden beams with reciprocating saws.

The building under construction is a so-called tank shop, which shelters large lobster tanks.