Three construction workers were injured, one seriously, when a steel frame scaffold partially collapsed at the Port of Long Beach Friday.

The collapse occurred just after 2:10 p.m., though the cause of the collapse was not immediately known, according to Brian Fisk of the Long Beach Fire Department.

Two workers were treated at the scene and released, but the third was seriously injured when a steel beam fell on top of them and was taken to a hospital for treatment.

A fourth construction worker was reported to have fallen into the water during the collapse, but was not injured, according to the LBFD.