Four Yarmouth firefighters and one police officer were injured Friday morning after an exterior stairwell collapsed as they evacuated someone during a medical emergency.

The stairwell collapsed about 5:52 a.m. as Yarmouth Police Department and Yarmouth Fire Rescue personnel removed a person from a third-story Sligo Road apartment, police said. Including the patient, there were six people on the staircase when it collapsed.

Everyone involved in the collapse was brought to Maine Medical Center and Mercy Hospital — both in Portland — with injuries that were not life-threatening, police said. The Freeport Fire Department helped transport the injured.

The Yarmouth police said that the Maine Department of Labor has been notified — as has the local code enforcement officer — and that an investigation was ongoing.