A gunman killed one person and wounded four others at a gym in Washington DC’s Logan Circle neighbourhood on Thursday morning, before shooting himself during a standoff with police in the apartment building above it. The suspect is dead.

Police said the first emergency call came in just before 8am, reporting gunfire inside VIDA Fitness. Officers reached the scene within about 30 seconds, according to interim Metropolitan Police Chief Jeffery Carroll. One person was found fatally shot inside the gym. Four others were hit by gunfire in and around the facility. One of the wounded is in critical condition, while the other three have injuries that are not life-threatening.

Officers traced the suspect to the residential building above the gym and found he had barricaded himself in a seventh-floor apartment. Negotiators spoke with him for more than an hour. Police then heard a gunshot from inside, forced entry and found him with a gunshot wound.

Authorities first described him as “contained,” and he was later confirmed dead from what appears to be a self-inflicted wound. Witnesses were evacuated from the gym in the hours that followed, and residents in the area were told to shelter in place while the scene was cleared.

Carroll described the suspect as a white man and said police believe he was a member of the gym. Investigators believe the attack stemmed from a conflict between the suspect and the building’s homeowners association, though Carroll stressed that a motive has not been formally established.

Police had not publicly named the suspect or the victim at the time of the briefing. Carroll described the scene as fluid, and the investigation is ongoing.

Gym-goers at the scene described the moment gunfire broke out. One regular said he was on a treadmill when he heard a loud pop, which he first took for a burst exercise ball, before turning to see a victim on the floor.