A gunman shot one person dead and wounded four others in an upscale neighbourhood of downtown Washington, United States, on Thursday before barricading himself in his apartment and killing himself, police said. The shooting, about a mile north of the White House, set off a massive police response in the nation's capital, with dozens of law enforcement vehicles racing to the scene and police helicopters hovering overhead.

Jeffery Carroll, Washington's interim police chief, told reporters the gunman fatally shot one person in a fitness centre attached to his apartment building and wounded four others before barricading himself in his apartment. He said the man fired at least twice at police through his apartment door before shooting himself, and that he had been pronounced dead at the scene. The man, who was not identified, was apparently in "some sort of a conflict" with the homeowners association of the building in the Logan Circle neighbourhood, Carroll said. One of the four wounded was in critical condition, while the injuries to the others did not appear life-threatening.S1S2

Washington Mayor Muriel Bowser denounced what she called a "senseless act of gun violence" and said the White House had been briefed on the incident. The shooting occurred during the busy morning rush hour, snarling traffic as police closed streets around the area. Some residents were evacuated by police while others were told to shelter in place.S1

Michael Carney, a member of the VIDA Fitness gym, told The Washington Sun he was on a treadmill when the shooting began. He said he heard a "pop" and then saw someone on the gym floor who had been shot in the head. "Everyone was kind of just hiding behind planters and stuff," Carney said. Logan Circle is one of the most expensive neighbourhoods in Washington, known for chic restaurants and nightlife, and sits a short distance from a heavy concentration of foreign embassies.S1