NEWELLTON, N.S. -- An emergency official says three workers were injured, one of them seriously, when the roof of a building under construction in southwestern Nova Scotia collapsed Thursday.

Mike Swim, station chief at the Island and Barrington Passage Fire Department, says the three men were working on the building near the wharf in Newellton when the roof came down around 5:30 p.m.

Swim says two of the men escaped from the building with minor injuries, but the third was badly hurt as he fell from the roof and was trapped in its trusses.

He says the man was rescued after firefighters spent 45 minutes cutting through the trusses with reciprocating saws.

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

Stacey Brown, a spokeswoman for Emergency Health Services, says a helicopter and three ambulances were dispatched to the scene, but the helicopter crew was told to return to their base.

Newellton is a small community on the north side of Cape Sable Island, about 250 kilometres southwest of Halifax.