A teenager is in a critical condition after he was shot in the head on his doorstep following a row in north London.

The 18-year-old was shot just before 3.30pm on Tuesday on Denmark Road, near Turnpike Lane in Haringey. Paramedics and an air ambulance crew treated him at the scene before he was taken to a central London hospital.

A resident living near the scene, who did not want to be named, said she had called police after hearing shots and finding the youth, named locally as Jojo, lying injured in the street.

“It was one of the boys who lives on the estate, 18, shot in the head,” she said. “His friend was holding a shirt to his head and he took it away at one point and my friend said put that back.

“I know the boy so I was just kind of feeling for him, because he kept going in and out of consciousness … I can’t get the look on his face out of my head, to be honest with you. It was just that kind of shock-horror petrified look in his eyes, so scared.”

The teenager was with his brother and a friend when he was shot, the neighbour said. Police and paramedics arrived within minutes and treated him at the scene before taking him away with his mother, in an ambulance, she added.

There have been no arrests and the Metropolitan police is appealing for witnesses. The shooter has been described as a man of Mediterranean appearance, with olive skin, aged about 18. He was with another man, who was described as black and also about 18.

The two men were thought to have came from the direction of Turnpike Lane tube station. Afterwards, it is thought they escaped on bicycles towards High Street.

Detectives from the Trident and area crime command, which deals with gang-related crime and all non-fatal shootings, are investigating whether the incident was linked to an earlier one involving the victim and his brother.

Police said that at about 1.30pm on Tuesday the brothers were driving along High Street, near the junction with New River Avenue, when one person in the car noticed a man he knew on a bike. The car stopped and the victim and his brother had a row with the man.

DCI Dan Brown, who is leading the investigation for Trident, said: “The man involved in the altercation has been described as having olive skin. The row happened in the street, and I’m sure will have been witnessed by a number of people.

“This was a bold attack in broad daylight on the victim’s doorstep and I want to hear from anyone that knows who the suspects are or who may have vital information for us.”

Paul Tuffery, 61, who lives down the road from the shooting, said he heard “a couple of cracks” and shouting at about 3.30pm.

“There was shouting, it sounded like kids screaming but round here there’s always kids screaming, and next minute helicopters came over, the air ambulance, and police closed off the road and they landed down the bottom,” he said.

“They were there for quite some time because they were treating the one that got shot – he was on the ground.”

Several neighbours spoke of gangs of youths hanging around the area, smoking cannabis and apparently dealing drugs. Two years ago the area had been affected by another shooting.

“Most of the people who come to [hang around in] this area don’t even live here,” one neighbour, who preferred not to give her name, said. “I’ve called the police so many times about them. They smoke weed out there and I called the police so many times because the smoke goes up to my flat and I get lightheaded.”

A London ambulance service spokesperson said paramedics were called at 3.35pm. “We sent an ambulance crew, a single responder in a car, an incident response officer and a hazardous area response team to the scene alongside London’s air ambulance,” the spokesperson said.

“The first of our medics arrived at the scene in under five minutes. We treated a man at the scene and took him as a priority to a hospital in central London.”