The accident happened just before noon at a construction site near Wilson Avenue and Highway 400, the Canadian Broadcasting Corp. reported. The victim's name had not been released.
The city issued a statement saying the work site was managed by Rabcon Contractors Ltd., which is under contract with the city to install new sewer connections for an industrial building.
"The city of Toronto offers its sincere condolences to the family and colleagues of this worker," the statement issued by the city said.
The Labor Ministry was investigating the incident. The city said it was fully cooperating with the investigation.
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