A doctor who was locked in a lengthy legal dispute with his condominium association after alleging his penthouse suffered mold and water damage costing him hundreds of thousands of dollars is suspected of opening fire Thursday morning at a Washington, D.C., gym.

One person was killed and multiple others were injured as the rampage unfolded in the trendy Logan Circle neighborhood, just a mile from the White House, drawing a rapid law enforcement presence. The suspect, Dr. Matt Lambert, was found inside his condo at the Metropole, a seven-story luxury building, dead from an apparent self-inflicted gunshot wound, officials said.

The gunfire erupted just after 8 a.m. at the VIDA fitness center, located on the street level at the Metropole. A man on a treadmill said that when he heard the first bang he thought it was a popped exercise ball.

Another witness told NBC News that he also heard a loud noise and saw a person in a chair fall with “blood coming from his head.”

A fire alarm went off and panicked patrons raced for the exit; several fled to a nearby bagel shop to shelter in place.

A federal law enforcement official and a local law enforcement official told NBC News that the suspect had gone to the gym to target a specific person; he left others unharmed. He then walked out and sprayed bullets before returning to his unit and barricading inside, the officials said.

From his apartment’s balcony, the district’s interim police chief said, the gunman struck four people who were on ground level. He also fired shots into the hallway through the door before turning the gun on himself, according to officials.

Building manager James Stuart, 46, of northwest Washington, D.C., was killed in the shooting, according to Jeffery Carroll, the interim chief of the Metropolitan Police Department.

Carroll said that three of the survivors of the shooting rampage had “non-life-threatening injuries,” while a fourth was in critical condition.

“We do know that there has been an ongoing dispute between the suspect in this case and the building, condo, homeowners association management regarding maintenance issues, mold and the like,” the interim chief told reporters at an afternoon briefing. “That there was a civil case that he filed against them. So we believe that it’s related to that.”

The attorney representing Lambert in the legal case involving the condo association said Stuart was a “central fact witness” in that case.

“He was also very pivotal in relaying information to the [apartment housing] board, I believe,” the lawyer, Joel Braithwaite, told reporters Thursday evening.

Lawsuit alleges condo damage

Lambert, 55, had been engaged in litigation with the Metropole Condo Association and EJF Real Estate Services Inc., the building’s property manager.

In a March 2025 complaint filed in the Superior Court of the District of Columbia and amended in July, Lambert alleged water damage to his seventh-floor unit was the result of façade remediation that reached the complex’s northeast corner, where his condo is, in 2024. Property records show he purchased the unit for more than $1 million in 2016.

From March 2024 to August 2024, Lambert said in the complaint, EJF and its engineering consultant conducted at least three leak-testing and investigatory procedures over “recurring water intrusion” into his unit. The property manager had the opportunity to identify, disclose and remediate the “ongoing moisture intrusion,” according to the complaint.

Workers had even cut into the unit’s drywall to determine whether water was running behind the wall and collecting excess moisture, the suit said. Lambert alleged there was visible mold, also detectable by smell, and said he had gotten two independent assessments completed. Despite findings “confirming elevated moisture conditions, mold growth and water intrusion,” Lambert added, Metropole and EJF “failed to implement appropriate corrective action sufficient to remediate the conditions.”

At a meeting in October 2024, Lambert alleged that an EJF representative dismissed his concerns and said the odor from the mold “smelled like cologne.”

The lack of action led Lambert to hire his own workers to mitigate the mold contamination, he said in his suit. The situation grew so bad, he said in his filing, that it caused damage in excess of $300,000 and led to the “loss of use and enjoyment of his home.”

Pictures included in his complaint showed his condo before the damage: floor-to-ceiling sweeping views of the Logan Circle neighborhood, a shrub-lined balcony and a spiral staircase. He also included pictures of what he said was the black mold uncovered in the walls and the unit left in disarray from remediation work.

His lawsuit alleged gross negligence and breach of fiduciary duty, and Lambert had sought compensatory damages and related costs he said he incurred, including for inspection, testing, temporary housing, relocation and storage.

The litigation was ongoing, and a remote mediation session was scheduled for March, according to court filings.

Lambert’s attorney, Joel Braithwate, told reporters Thursday evening that they had spoken on Tuesday and that Lambert seemed to be in a good place as his civil case continued.

The Metropole Condominium Association and EJF representatives and their attorneys did not immediately return requests for comment Thursday. The defendants denied the allegations in an answer to Lambert’s amended complaint.

The condo association also filed a complaint in December 2025 naming other parties, including Urban Adventures Companies Inc., which operates the Vida fitness center, as the reason for any damage to Lambert’s unit. The complaint alleges that the gym’s dryers and a failing exhaust system “likely caused” elevated moisture levels and cites the findings of an engineering consulting firm retained by Metropole.

A lawyer for VIDA did not immediately respond to a request for comment.

Vented on social media

Lambert had regularly documented his feud with his building on social media, posting on X under the account name “OfMiceandMold.” In a post at 8:06 a.m. Thursday, he shared what he said was an engineering report about the damages to his condo, a day after he also posted pictures of the remediation work he said was necessary.

“Two years of living in luxury (and the start of 6 months with no shower, dryer, HVAC, and cooking),” he stated on the account.

Braithwate said Lambert, who founded a healthcare and technology consultancy company called MLEM, was in Orlando, Florida, this week for a speaking engagement and was preparing to start a new job on Monday in the medical and artificial intelligence field.

He said that he never knew Lambert to be a gun owner and they had never discussed firearms.

Metropolitan police said three weapons were recovered from his condo: a handgun, a rifle and a shotgun. It’s unclear how the shooter obtained the weapons, but Lambert did not have firearms registered to him in Washington, D.C., the police chief said.

“We know that he used each of those firearms” on Thursday, Carroll said, adding that authorities believe “there was some level of planning associated” with the shooting rampage.

Public records indicate Lambert had hunting licenses over the years in Alaska, Montana and Oregon.

In one of the complaints about his condo on social media, he mentioned a new resident in April who said they had no hot water in their unit.

He wrote: “If you’re looking for the building manager, I would check the gym.”