The gunman in Thursday’s deadly gym shooting in Washington, D.C., has been identified by law enforcement sources as Dr. Matt Lambert, who had an apparent dispute with his homeowner’s association.

Lambert’s identity was confirmed by a pair of law enforcement officials and a person familiar with the matter who spoke to The Associated Press on condition of anonymity.

Authorities said the shooter opened fire around 8 a.m. inside VIDA gym in D.C.’s Logan Circle neighborhood. One person was killed and four others were wounded. The gunman was also killed.

DC GYM SHOOTING KILLS 1, INJURES 4; GUNMAN DEAD, SOURCES SAY

According to a report from The Associated Press, the shooter had an ongoing issue with building management at his apartment building and filed a lawsuit against the company last year.

LISTEN: DC shooting dispatch audio reveals 30 people sheltered in gym basement as gunfire erupted

Less than 10 minutes before the first calls about the gunfire came in, according to the AP, Lambert appeared to post on an account on X named “OfMiceandMold” posted on the platform, “My manifesto is an engineering report,” with screenshots of that report.

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General view of the cordoned-off area following a shooting in Washington, DC, US, November 12, 2026. (REUTERS/Aaron Schwartz)

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The photos show the dispute between Lambert and Metropole Condominium Association with problems like “mold” and “water intrusion” issues.

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The account features numerous posts, photos, and videos of alleged issues inside the apartment. In a post made at the beginning of October, he called out his HOA for what he said was “months of ‘Luigi’ tactics” and mentioned submitting “an independent engineering report.”

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The shooting is still under investigation.

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