The incident happened on Monday, August 8, at around midday, in the road, near Rossland and Westney streets.
Ornge Air Ambulance attended the scene and transported one person to the hospital, Durham Regional Police told CTV News.
Ornge said their patient was a man in his 20s.  He was taken to Toronto’s Sunnybrook Health Sciences Center with serious injuries, they said.
Another male victim has been taken to a local hospital, Sgt.  Joanna Bortoluss, of Durham Regional Police, told media at the scene. 
The extent of this victim’s injuries are unknown at this time.  
Bortolus said two other workers remain trapped in the trench at this time.
Motorists should note that Rossland Roads between Ravenscroft and Westney will be closed for several hours as police investigate.
The Ontario Ministry of Labor is now on scene and investigating.