Crews rescued three workers left hanging by ropes about 15 stories high at a downtown Indianapolis building after scaffolding collapsed.

The scaffold was left hanging almost vertically along the side of the 31-story M&I Bank building following the accident Thursday afternoon.

A rescuer rappelled down the side of the building to the workers, who were hanging by their safety harnesses. It was not immediately known whether the workers suffered any injuries.

Authorities did not immediately say what caused the collapse.