SIOUX FALLS, S.D. (KELO) — OSHA has joined the investigation into a scaffolding collapse on the Sanford Health campus in central Sioux Falls.

The collapse Thursday afternoon sent three construction workers to the emergency room with injuries, but there are no updates on how they are doing. The incident happened in the area between the Surgical Tower and the Children’s Hospital where a new orthopedic center is being built.

OSHA has compliance officers interviewing people. OSHA says no other information will be released until it completes its investigation, which could take up to six months.