Watch: Terrifying moment worker dangles from crane at Canadian construction site

A witness standing off-camera can be heard saying: "Oh my God, how the f**k did this happen?"

Distressing video has captured the moment a construction worker was left dangling more than 100 metres in the air from a crane after a potentially deadly mishap in downtown Toronto.

In a minute of terror, the worker can be seen hanging on to a cable for dear life as a heavy load sat just metres above him.

The crane operator was lowering the load, seemingly unaware a worker was dangling beneath.

A witness standing off-camera can be heard saying: "Oh my God, how the f**k did this happen?"

Others could be heard shouting: "Oh my God, hang on! Holy f**k, Jesus Christ."

"Somebody tell them to stop before he gets crushed."

A witness standing off-camera can be heard saying: "Oh my God, how the f**k did this happen?"

According to the construction company the worker's hand was "entangled with a tagline after hooking a load".

"Fortunately, he was safely lowered to the work surface and not seriously injured," PCL Constructors Canada Inc said.

This is the terrifying moment a worker was left dangling dozens of metres above the ground surrounding sky scrapers in Toronto. Photo / @my_s1/ Instagram

Onlookers could be heard screaming at the crane operator to stop, fearing the heavy load above the dangling worker would crush him.

The worker in the video is employed by Modern Niagara as a rigger, responsible for ensuring loads of materials are securely fastened before being hoisted by crane operators, PCL said.

Ontario's Ministry of Labour, Immigration, Training and Skills Development confirmed it sent an investigator to the site on Wednesday.

"It was reported that a worker became entangled with a tag line from a crane after hooking a load, was hoisted off the podium level and sustained injuries."