Reports suggest that it was a 500-tonne Liebherr all terrain operated by Baldwins.
The jib was being lowered having completed work at the 20-storey Cruddas Park flats in Newcastle.
Eyewitnesses were quoted by the Newcastle Chronicle saying that the jib was half way down when it crashed, with a cable whiplashing one of the workers, having apparently snapped.
A man was taken to hospital with facial injuries.
“During this process, a site operative unfortunately sustained a minor injury and as a precautionary measure was attended to by the emergency services.
“We have instigated an internal investigation to determine the factors behind the incident and in the meantime, we are working closely with (client) Your Homes Newcastle to ensure they remain fully informed of the situation."