This is the dramatic moment when a crane topples over from the weight of a concrete slab - leaving workers clinging to the base as it overtuners.

The boom truck was removing the huge counterweights from the rear of a tower crane at a construction project in Heilongjiang, China, on October 10.

But the operator appeared to have misjudged the weight of the load, causing the black and green truck crane to fall over.

Two workers who stood on one of the truck's hydraulic legs while trying to keep it weighted down were lifted in the air. They were unable to hold on and fell around 12ft to the ground.

The two men violated the rules and stood on the crane's counterweight position, according to health and safety experts.

According to local businesses, the accident occurred several days ago while unloading the tower crane, resulting in serious injuries for both workers.

Local media reported that one of the men had five broken ribs and the other had multiple stitches on his buttocks.

The construction site is still operating normally.

The Emergency Management Bureau of Beilin District stated that an investigation is underway, but further details cannot be disclosed at this time.