Three workers were injured, one of whom was trapped for hours and suffered life-threatening injuries, after a catwalk collapsed inside the old Boston Edison power plant in South Boston Wednesday afternoon, officials said.
Police, fire, and ambulance crews raced to the 19th century building, the site of a major construction project, shortly before 2 p.m. for what Mayor Michelle Wu called a “very dangerous rescue operation.”
Boston Emergency Medical Services took two of the workers to Boston-area hospitals shortly after the collapse. A third worker was extricated after being trapped in the rubble for three and a half hours and taken to a hospital with life-threatening injuries, according to Sergeant Detective John Boyle, a police spokesman.
Wu lauded the response of emergency workers who responded to the iconic red-brick industrial building.
“I’m very grateful to our first-responders today,” Wu said at the scene.
The most severely injured worker was on the first floor when the collapse occurred. A 30-foot section of concrete that fell from the second floor pinned his legs to the ground, Brian Alkins, a spokesman for the Boston Fire Department said. Working in a tight space with the risk of further collapse looming, firefighters carefully cut a hole through the concrete to free the man.
“There’s a large piece of flooring that collapsed,” Boston Fire Commissioner Jack Dempsey said. “It was cantilevered, which means it was sticking out over. It collapsed [and] formed a void, which knocked the man back, and part of that ... landed on his legs, his lower legs, and it trapped him.”
“As I said with the other accident we had, demolition jobs are very dangerous,” he later added. “Probably more dangerous than putting buildings up. ... Look how old this building is. We’ve had a lot of serious problems with this building over the years.”
A surgeon responded to the scene while the man was trapped because his injuries were considered life-threatening, officials said.
Steven McHugh, Boston EMS deputy superintendent, said the three victims were taken to different hospitals: Massachusetts General Hospital, Boston Medical Center, and Tufts Medical Center.
The catwalk collapse marked the latest in a string of serious, construction-related accidents in the Greater Boston area, including a partial building collapse on the site of a multiuse development project near Government Center that killed a demolition worker in March.
Wu addressed the recent incidents at Wednesday’s press conference.
“I’m angry that we’re here again at another worksite with another major incident,” she said.
“Every worker, every family member of workers across our city need to know that it cannot be a question whether your family will come home at night, whether they will be safe on the job,” she added.
Investigators were working Wednesday to determine what caused the catwalk to collapse.
The accident was reported to Boston police at 1:43 p.m., when officers responded to 776 Summer St. for a report of a partial building collapse with “multiple people” trapped at a construction site.
The development is a joint project of Hilco Redevelopment Partners and Redgate Real Estate, with construction managed by Suffolk Construction. The companies plan to transform the 15 acre site, which includes the old power plant, into offices, apartments, and stores, along with a hotel and nearly six acres of open space, much of it along the water.
The accident occurred during the demolition phase inside the Edison power plant building.
In a statement Wednesday night, Suffolk said, “Our thoughts are with the individuals who were injured, along with their families. We are currently on site working closely with [the Occupational Safety and Health Administration], our subcontractor and the local authorities to determine the cause of this incident and confirm the safety of the site.”
A spokesperson for Hilco said, “The safety of the workers on site and in the surrounding areas is our top priority. We are thankful for the swift response from Boston emergency services.”
The force of the collapse could be felt in at least one nearby office building.
Kyle Merchant, 28, who works across the street from the worksite, said he felt the floor shake.
“A lot of times different trucks will go by, but [this] just felt a little bit differently,” he said.
Merchant went to the window and looked out at the street.
“Probably no less than 10 minutes later, all of a sudden, you know, 40 people all were walking out, getting as rapidly out of the building as possible,” he said.
As whirring sirens and emergency vehicles with flashing lights filled the area, several public officials responded to the scene, including Wu, City Council President Ed Flynn, and Suffolk District Attorney Kevin Hayden.
Summer Street was closed between the Summer Street Bridge and First Street for a few hours, and sections of the road outside the construction site were roped off with yellow police tape.
Wu said the site’s work permit will be temporarily paused while OSHA investigates.
According to a federal database, OSHA has performed 13 inspections at Suffolk job sites in the last five years, but none have been at 776 Summer St. Of those inspections, 11 have been completed and have resulted in zero citations, and two are still open, data show.
Danny McDonald and Jessica Rinaldi of the Globe Staff and Globe correspondent Matt Yan contributed to this report. This is a breaking news story that will be updated when more information becomes available.