Thirty-one construction workers have been rescued from a huge industrial tunnel that partially collapsed in the Wilmington area of Los Angeles on July 9, the Los Angeles Fire Department (LAFD) said.

The incident happened at about 8 p.m. local time at Los Angeles County’s Clearwater Project, a nearly $700 million effort to carry treated wastewater from across the county to the Pacific Ocean.

The affected people, all believed to be tunnel workers, were safely removed and had no visible injuries, the LAFD said in a statement.

The fire department noted that no people were missing.

More than 100 LAFD responders were deployed to the scene, including Urban Search and Rescue team members specially trained, certified, and equipped to handle confined-space tunnel rescues, according to the fire department.

The tunnel is 18 feet wide and will stretch seven miles once completed.

According to the fire department, the cave-in occurred at an undetermined depth at an underground horizontal excavation site roughly five to six miles south of the sole entrance.

“The precise number of workers trapped behind the collapse has yet to [be] confirmed,” the department said in a statement. “Preliminary reports are that the trapped workers were able to scramble with some effort over a [12-foot- to 15-foot-tall] (undetermined length) pile of loose soil, to meet several coworkers on the other side of the collapse, and be shuttled several at a time by tunnel vehicle to the entry/access point more than five miles distant.”

LAFD Fire Chief Ronnie Villanueva told reporters at a media briefing that 27 people were initially trapped but that four workers entered the damaged section of the tunnel to help rescue the others.

“The workers had to climb through debris” before they were assisted out, Villanueva said.

Video footage shared online showed dozens of rescue teams surrounding the structure and using a crane to lower a lift into the tunnel while multiple fire trucks surrounded the perimeter of the industrial site.

Robert Ferrante, chief engineer and general manager of the LA County Sanitation Districts, told reporters at the media briefing that a section of the part of the tunnel that was already built had experienced squeezing ground conditions, leading to the partial collapse.

Authorities are still investigating the exact cause of the collapse. Work will not resume until the project contractor assesses what happened and deems the site safe, authorities said.

LA Mayor Karen Bass said at a news conference on July 9 that she had spoken with the individuals who were rescued and made sure that they were able to reach their family members, who had been anxiously waiting at the site for news following the collapse.

“All of the men that were in that tunnel [are] rescued, up, safe,” Bass said. “I just have to tell you that we’re all blessed today in Los Angeles.”

In a separate post on social media platform X, Rep. Nanette Barragán (D-Calif.) said tragedy had been avoided because of LAFD’s swift actions, noting that the fire department “sprang into action immediately when [it] got word of workers trapped deep underground.”

Barragán said she was relieved to see that the workers are all safe and accounted for.

“Thank you to our first responders whose bravery and speed saved lives,” the lawmaker wrote. “We must never forget that behind these large-scale infrastructure improvements are workers—real people—doing difficult and dangerous jobs. We are so grateful they are safe and will go home to their loved ones tonight.”

The Epoch Times contacted the LA County Sanitation Districts, which is the agency in charge of the project, for further comment.