The scene on Primrose Hill on Tuesday where 21-year-old Finbar Sullivan, right, was killed [Metropolitan Police]

A MURDER investigation has been launched after a 21-year-old man was fatally stabbed in a packed-out park on Tuesday evening.

Finbar Sullivan, who had been filmmaking student at London Screen Academy in Highbury, was killed at the top of Primrose Hill.

LSA Principal Sam Summerson yesterday (Thursday) described Finbar as a “kind, thoughtful, and valued member” of the school, and said he had been “a delight to have in class”.

Mr Summerson added: “We are heartbroken by this tragic news and by the loss of such a bright young life. Finbar was a talented young filmmaker with a real passion for the subject, and he was known for his warmth, curiosity and engaging spirit. He made a strong impression on staff and fellow students alike during his time at LSA.”

On Tuesday, hundreds of people had been watching the sunset from the park when police and ambulances were called to reports of a fight on Primrose Hill at 6.41pm.

Despite the efforts of paramedics, Finbar died at the scene.

Police are continuing to appeal for witnesses, and at the time the Tribune went to print, no arrests had been made.

Mr Sullivan was an avid filmmaker who had aspirations to become a cameraman, following in the footsteps of his grandfather Michael Seresin who had worked on films like Harry Potter and the Prisoner of Azkaban and Rambo III.

According to his father Christopher Sullivan, the 21-year-old had gone to the park to use the camera bought for him as a birthday present.

Speaking to the Daily Mail, Mr Sullivan said: “This is the worst tragedy I could ever imagine. He’s my only son. He can never be replaced.

“I’m so broken-hearted, I can’t believe it. He was the most beautiful, lovely, outgoing, loving boy.

“He was just a really lovely person. And why he was targeted we have no idea.”

Finbar had attended Acland Burghley school in Tufnell Park, and had produced music videos for drill artists under the name Sully Shot It.

His father described him as a “studious kid”, who spent six nights a week at home editing footage. “We were just about to start a company together,” said Mr Sullivan. “He was going to do his showreel today with me. And now he’s dead.”

In a report following his final project at LSA, his teacher had written: “You have always been a joy to teach and have always been extremely polite, well mannered and responsive to feedback, which are important personal traits that I’m sure will see you go far in the industry.”

Detective Inspector Andy Griffin, who is leading the police investigation, said: “Finbar’s family have suffered a devastating loss and our thoughts are with them as they navigate this very challenging time.

“Our investigation is progressing at pace and we are following several lines of inquiry. This incident occurred in a busy, public park and there may be many witnesses who can help us piece together what happened.”

Footage circulating on social media shows a knife fight break out on the hilltop, with one man lunging towards another brandishing a knife as onlookers back away.

Another man, also suffering with stab wounds and thought to be in his 20s, ran out of the park into the Queen’s Pub in Regent’s Park Road, before being taken to hospital, where his injuries were found to be neither life-threatening nor life-changing.