The incident happened at Oldpark Road shortly before 7.30pm on Friday.
Up to 10 shots were fired at 24-year-old Sean Corbett who had just left a shop and was standing beside a Seat Toledo car.
He was taken to the Mater hospital and he later received emergency surgery.
His uncle Darren Corbett said he felt sick when he heard the news.
"His mother is in a bad way," he told UTV. "Nobody knows what to think. He's only a young kid."
He said he doesn't know why his nephew was targeted by the gunman.
"Nobody knows if it is a paramilitary group, nobody knows whether it is a feud between him and somebody else."
Another man, aged 22, who was inside the car, was also shot multiple times.
He drove himself to hospital where he was also treated for gunshot wounds.
Both men are currently in a stable condition.
Police have described the incident as a "reckless and callous attack" which put up to 40 people at risk, including women and children.
"This type of attack is unacceptable in our community - no one deserves to be hurt or injured in this way and no one has the right to put the safety of so many at risk," North Belfast Area Commander, Chief Inspector Andy Freeburn said.
Two people have been very seriously injured but we are lucky that we are not dealing with many more casualties today.
CI Andy Freeburn
A police investigation has been launched and an enquiry team is looking into the circumstances of the shooting.
"We will do everything we can to find those responsible and bring them before the courts," CI Freeburn continued.
"The help of the local community is vital in helping us create a clear picture of this attack and we would ask for their support as we conduct our enquiries.
"I would appeal to anyone with information to contact detectives in North Belfast on 0845 600 8000."
It is the second shooting in 72 hours in north Belfast.
On Tuesday night an 18-year-old man was shot in the thigh and buttock in the Ardoyne area.
Local politicians have condemned the latest attack.
These are the actions of people who care nothing for the well-being of society and who are prepared to murder and intimidate to advance their own interests.
Nelson McCausland, DUP MLA
North Belfast DUP MLA Nelson McCausland appealed for witnesses to come forward.
He said: "It is important that the police rapidly determine the nature of this murderous attack - did this involve republican paramilitaries or criminal gangs?"
North Belfast Sinn Féin MLA Gerry Kelly said the community has been left frightened.
"This was at a number of shops and places of business where people were going in and out," he said.
"We're very lucky, I understand, that we're not dealing with two deaths this morning. There could have been other people shot as well."
"Whoever is involved in this, they need to stop, the community is absolutely against them and anybody that has any information to do with any of these shootings need to bring it forward and get these people off the streets."
SDLP Oldpark councillor Nichola Mallon said she was repulsed by the attack.
"This latest incident represents not just an attack on the two men who have been shot but on the wider community. Those that resort to such cowardly and violent attacks have no place and serve no purpose for the people of North Belfast," she said.
"We are seeing a worrying disregard for human life and an escalation of street violence which is totally unacceptable."
Alliance East Antrim MLA Stewart Dickson said the event had "inconvenienced a whole community".
"My thoughts are with the victims and their families," he said.
"I would call on anyone who can assist catch those behind these shootings to contact the PSNI as soon as possible.
"It is only when the community backs the police in their fight for justice that we can begin to rid our streets of this behaviour."