Police have ruled out dissident republican involvement in the murder of former IRA commander Gerard "Jock" Davison.
Mr Davison, 47, who was investigated for a killing which rocked the Northern Ireland peace process, was gunned down close to Belfast city centre this morning.
He was hit a number of times while walking along Welsh Street in the staunchly republican Markets area at about 9am.
Detective Chief Inspector Justyn Galloway, who is leading the murder hunt, said: "I do not believe it is sectarian.
"I do not believe dissident republicans have been involved. However, we will keep an open mind as information comes into the inquiry."
Mr Davison was allegedly involved in the fight that led to the death of Belfast man Robert McCartney in January 2005 and was among three IRA members expelled following an internal investigation in the wake of the death. He was questioned by police but released without charge.
It is understood the father-of-three who was also a grandfather had been making his way to a community centre where he worked when he was attacked.
Police have declined to disclose the number of gunmen involved in the shooting; whether they were masked or how they fled the scene.
They have also refused to confirm if Mr Davison was known to have been under death threat.
DCI Galloway added: "Many people in Northern Ireland have a past, but that is in the past and there is no justification for the gunning down of this community worker.
"We are working to establish a motive.
"It would be remiss of me at this stage to speculate on what the motive may be. But, we are not ruling anything in or out in relation to why Mr Davison was attacked."
As the IRA officer commanding in Belfast, Mr Davison was one of the most well-known republican figures in the city.
He backed Sinn Fein's peace process strategy following the 1998 Good Friday Agreement and was employed with the Markets Development Association as a community worker.
Sinn Fein South Belfast Stormont assembly member Alex Maskey said: "What we have had here today is a very brutal killing of a local man.
"He is a very well-known person in this area. His family are well-known and he is very well-regarded in this area as a long-standing republican."
There was a heavy police presence in the Markets for most of the day.
A large cordon was put up around the scene and police forensic tent was erected over the victim's body.
At the police lines, small groups of local people and a number of high-profile Belfast republicans huddled together in driving rain looking on at scenes-of-crime officers in white forensic suits carrying out detailed examinations.
Most people were reluctant to speak about the shooting but have expressed shock.
Mr Davison's remains were removed in a hearse at about 2.30pm.
Robert McCartney's sisters, who were forced to move out of the Markets, led a long-running battle for justice for the killing of their brother, following a bar argument, which took them to the White House.
The killing happened at a time when Sinn Fein was under pressure to accept the rule of law in Northern Ireland. Its decision to support the police two years later led to the formation of a ministerial executive at Stormont and the sharing of power between republicans and the DUP.
Mr Davison's uncle, Terence Davison, was later acquitted of Mr McCartney's killing.
David Ford, justice minister in the devolved power-sharing assembly at Stormont, condemned the killing of the community worker on the eve of the General Election.
"There can be no excuse, explanation or rational reason why another family should be made to suffer through the taking of a life. Those who carried out this heinous crime have no place in our community."
SDLP leader Alasdair McDonnell said: "This is a horrendous crime and those responsible have shown no regard for anyone that could have been caught in the middle of it during the school rush hour. Witnesses have described how the man was shot in the street.
"My thoughts and prayers are with the individual's family at this traumatic time. People here want to move on from the violence of the past. This community will reject those who bring murder and mayhem to our streets. I would appeal to anyone with any information to bring it forward as soon as possible."
Sinn Fein leader Gerry Adams described the murder as a "brutal act" and said it would be condemned by "all sensible people".
The PSNI has set up an incident room at Musgrave Street police station and is appealing for witnesses to come forward.
DCI Galloway said: "This has been a callous shooting.
"It has occurred at a time when there are many people out on the street, at approximately 9am, children going to school, people going to work, and it is to those people who were in that street and who saw the shooting that we make this direct appeal to."
Anyone with information is asked to contact detectives on 101 or, anonymously through the charity Crimestoppers.