LONDON (Reuters) - Investigators refused to reveal on Wednesday whether a man found dead after an armed siege by police in the upmarket Chelsea area of London had been shot by specialist officers or had turned the gun upon himself.

A post mortem on barrister Mark Saunders, 32, was being carried out on Wednesday afternoon after he was found dead at a flat in fashionable Markham Square, just off the King's Road, after a five-hour stand-off on Tuesday.

The Independent Police Complaints Commission (IPCC), which has opened an inquiry, said it was too early to comment on the cause or nature of his death.

IPCC Deputy Chairman Ian Bynoe told reporters: "Until the post-mortem examination has been completed I have to keep an open mind ... and cannot answer your questions concerning the cause or nature of the injuries."

He said it was too soon to say whether the incident had been triggered by a domestic dispute, as some newspapers have reported.

One firearm, which was believed to have been lawfully owned, was retrieved from the house.

It is not clear how many shots were fired by police before they stormed the building, though there were three exchanges of fire between the gunman and police.

Colleagues of Saunders at his chambers, Queen Elizabeth Building, said they understood the married man was involved.

"He was a very valued member of chambers," a spokeswoman said.

"All his colleagues are shattered. We have no understanding of what happened. It is tragic."

Saunders specialised in family law, mainly matrimonial finance, and was included in the 2005 "up and coming" lawyers list. In the past, he was described as "popular, gutsy and polished" with a "maturity and unflappability".

The incident happened at the start of the Tuesday evening rush hour after reports a gun was being fired from the back of the flat into another house.

Police brought in a negotiator, but no hostages were involved.

Witnesses reported seeing a man carrying a shotgun and they said he had fired more than half a dozen shots.

Residents in nearby houses were told to lock their doors and stay away from windows.

The area around the King's Road, a fashion centre of Swinging London in the 1960s, contains some of the most expensive homes in the capital.

(Reporting by Avril Ormsby; Editing by Steve Addison)