Rescue crews recovered the bodies of two men who died when the trench they were digging suddenly gave way on Monday, police said.
Around midday, a large trench, near the Rossland and Westney roads, collapsed, injuring two workers and burying two others.
An Ornge Air Ambulance attended the scene and transported one person to the hospital.
A second worker broke his ankle and was taken to a local hospital.
A large number of firefighters and heavy excavation equipment were rushed to the scene, with crews slowly digging out and reinforcing the edge of the ditch overnight.
Around 2:30 a.m. Tuesday, Durham Regional Police said they found the bodies of the two missing workers.
They were carefully removed from the trench.
An Ontario Ministry of Labor investigation into what caused the collapse is ongoing.