A gunman in the United States killed a man in front of shocked gymgoers before shooting four more people during a rampage not far from the White House.

A witness has told how people had to step over the victim’s dead body to escape the scene in an upmarket area of Washington DC.

The gunman turned the weapon on himself while barricaded in his penthouse flat, where he had been speaking to negotiators, according to police.

He has been identified as a doctor named Matt Lambert, who was embroiled in a legal dispute with the building’s management over long-running mould and damp problems in his seventh-floor apartment, court documents show.

The capital’s mayor Muriel Bowser said she was “devastated” at the loss of life in a “senseless act of gun violence” and expressed her thanks to officers and other emergency workers who “contained this situation”.

The shootings happened on Thursday at around 8am (1pm UK) in Logan Circle, about a mile north of the US president’s residence.

An extensive cordon was in place with a heavy police presence, including Swat teams and federal agents.

A shelter-in-place alert was lifted shortly after 11.30am local time (4.30pm UK).

Jeffery Carroll, interim chief of the Washington’s Metropolitan Police Department, said one man died at the VIDA fitness centre, while one of those injured was in a critical condition.

James Spellman, who was at the gym, said there were about 50 people there when the gunfire started.