The security forces stepped up their presence on the Shankill Road last night amid fears of further retaliatory violence from feuding UVF and UDA-UFF loyalists following the murder of Mr Samuel Rockett.
Mr Rockett, who had connections with the UVF which killed two loyalists earlier this week, was shot on Wednesday night in front of his 18-month-old daughter and his girlfriend.
Security sources are viewing the killing as a UFF reprisal for the UVF double murder last Monday of two loyalists, Mr Jackie Coulter, who was an associate of the jailed UDA Shankill commander, Johnny Adair, and Mr Bobby Mahood, who was buried yesterday.
Mr Rockett was shot several times by two masked gunmen who burst into his girlfriend's house at Summer Street, in the Oldpark area of north Belfast, at around 10.20 p.m. He died in hospital soon afterwards.
Security sources said Mr Rockett came from a well-known UVF family and was viewed as an easy target.
It is understood he had been told by local UDA members he would be safe.
The killing came a day after the Northern Ireland Secretary, Mr Peter Mandelson, ordered that Adair be returned to jail.
Mr Rockett's uncle, Mr Steve Rockett, said his family was distraught. He said he had no doubt his nephew was killed as part of the loyalist feud.
"It has to end, it has to end. What's the sense in it?" he said.
A UUP Belfast councillor, Mr Jim Rodgers, who worked in a lower Shankill training centre where Mr Rockett trained as a mechanic up until 1998, described him as a well-liked man and said the community was stunned by his murder.
As security was stepped up in the Shankill area, calls for mediation between the loyalist factions appeared to go unheeded.
RUC sources predicted that more violence was likely to follow in the Shankill area.
"It's not settled. It's going to get worse before it gets better," said one source, who added that the UVF had relocated 47 families in the past week.
"The UVF is describing UDA boys as scum, an adjective they usually only use for the IRA," said another.
The Northern Ireland Secretary, Mr Peter Mandelson, said the killing of Mr Rockett took the loyalist feud to a new low.
"However long it takes for the present tension to subside, these rival organisations must recognise that continuing violence is getting them nowhere," he said.
"I appeal to them to accelerate their efforts to find a way of mediating their differences without constant resort to arms."
Mr Billy Hutchinson, of the Progressive Unionist Party, the political wing of the UVF, blamed Johnny Adair's UFF C Company for the murder.
"Of course, it was a UFF attack on a 21-year-old kid," he said. "I've been saying all along, mediation will have to come. It's a matter of time, but at the moment all of these calls for mediation are just going to fall on deaf ears. People have to pull back from the brink."
Mr Hutchinson blamed the security forces on the Shankill for allowing Mr Rockett's murder to happen while they were carrying out operations elsewhere. He said they had left the area wide open for attacks. Mr John White, the chairman of the Ulster Democratic Party, the political wing of the UDAUFF, admitted the murder appeared to have been carried out by the UFF as part of the feud.
"I am appealing for dialogue, but unfortunately it's falling on deaf ears," he said.
"I am telling everyone in both organisations to stop what they are doing now.
"They are causing so much damage to this community it's unbelievable and sooner or later they are going to talk and they should talk now rather than wait until there's another death."