The family of a Trainspotting actor who was murdered outside his home were inside the building when he was shot.
Bradley Welsh, 48, was killed at his basement apartment in Chester Street, Edinburgh, on Wednesday.
Police said his partner and young child were fortunate not to be caught up in the shooting.
Detectives believe the murder was a targeted attack on Mr Welsh, who also featured in an episode of Danny Dyer's Deadliest Men.
Det Supt Allan Burton said Mr Welsh was returning from the Holyrood Boxing gym he ran in the city when he was shot.
He said: "We know from witnesses who were nearby, and from house-to-house inquiries, that he had exited his motor vehicle and walked towards his home address.
"It's a basement apartment and he was making his way down the stairs and someone has attended at the top of the stairs and shot him.
"His partner and young child were in the house at the time this happened. So if they had been exiting the house, they could have been caught up in that and subjected to seeing their father and their partner die on the front steps."
Det Supt Burton added: "Any member of the community could have been walking by and been targeted by this individual.
"It's a real threat that someone is running about with a gun on the streets of Edinburgh."
One resident said he was told someone had been shot in the head and people were instructed to stay indoors as the street was cordoned off.
Armed officers were sent to the scene after receiving "multiple reports" of a firearm discharge.
Mr Welsh starred alongside Ewan McGregor, Ewen Bremner, Jonny Lee Miller and Robert Carlyle in T2 Trainspotting, playing the gangland figure Mr Doyle.
Trainspotting Author Irvine Welsh paid tribute to "his beautiful friend" on social media.
In Danny Dyer's Deadliest Men on Bravo in 2008, Bradley Welsh described himself as a "born leader".
He discussed his past as a Hibs Casual football hooligan in the 1980s.
Mr Welsh talked about how he "mobbed and robbed" and was involved with organised "smash and grabs" at stores, including Jenners in Edinburgh.
He later spent four years in prison for extorting money from estate agents.
In recent years, the boxer became involved in charity projects in Edinburgh, including helping young people to stay away from a life of crime through his boxing gym.
Detectives said they had no reason to believe Mr Welsh's shooting was a random attack and insisted the streets of Edinburgh remained safe for local residents and workers.
Det Supt Burton said: "It's unusual for there to be a shooting in Edinburgh.
"I believe this has been a single incident at this location - a targeted attack on Mr Welsh - and what we need to find out is who set it up and why."
Ch Insp David Robertson, local area commander for Edinburgh city centre, added: "We recognise and understand the profound impact this incident will have had, both on those connected to the victim and to the local community of the west end.
"There will naturally be a high officer presence in the area over the forthcoming days both to offer reassurance and gather any relevant information that may be of use to the inquiry."