BOSTON (AP) — Firefighters in Boston worked for more than three hours to rescue an injured construction worker after part of a historic power plant collapsed Wednesday while being redeveloped.

Fire Commissioner Jack Dempsey told reporters the worker sustained life-threatening injuries when a wall collapsed and landed on his legs and lower body.

Two other workers were quickly removed from the former Edison Power Plant in South Boston and taken to an area hospital with non-life-threatening injuries, he said. The collapse occurred at around 1:45 p.m.

Wednesday’s incident was the second collapse at a Boston construction site this year. A construction worker died in March when a part of a parking garage being demolished collapsed.

Mayor Michelle Wu credited first responders for executing a “very dangerous rescue operation,” saying it was a “near-miracle” that the worker was pulled to safely.

“For my part, I’m angry that we’re here again at another work site with another major incident,” the Democrat added, according to WCVB-TV.

The plant, which is over 120 years old, is being redeveloped into a mixed-use property that includes residential, office, research and retail space, a hotel, and open public space, according to the Boston Planning and Development Agency.

The federal Occupational Safety and Health Administration was also investigating, a spokesperson said.

Suffolk Construction, the company responsible for the deconstruction, said a catwalk had collapsed at the building, which is more than 120 years old. “We are currently on site working closely with OSHA, our subcontractor and the local authorities to determine the cause of this incident and confirm the safety of the site,” the company said in a statement.

Hilco Redevelopment Partners, which is developing the site, thanked first responders for their quick actions.