The men were taking down what little remains of the building when the concrete slabs they were standing on collapsed, sending them onto the debris-ridden floor below.
The accident happened just after 4.30 pm when the men, aged 23, 33 and 51, are understood to have fallen between 30 and 40 feet.
The Ambulance Service said today that the 23-year-old was thought to have fractured his ankle and leg, and had cuts to his back and legs.
The 33-year-old landed on his left-hand-side and had suspected fractures to his leg and pelvis, while the 51-year-old man may have fractured the top and bottom of his arm.
All three were taken to Accident and Emergency.
Police Insp Chris Beechey said: ‘The men have fallen from a height while working on the building site.
We are piecing together what happened.’ He added that the Health and Safety Inspectorate had visited the site and would be investigating what had happened.
