The victim was stabbed to death in High Wycombe, Buckinghamshire, in a "targeted attack", according to Thames Valley Police.

A second 17-year-old boy was also hurt in the Sunday evening attack but his injuries are not thought to be life-threatening.

Police are searching for four suspects, who all had their faces covered at the time, as part of a murder investigation.

No arrests have yet been made.

Detective Superintendent Kevin Brown, of Thames Valley Police, said: "We are in the very early stages of this investigation and details as to what has happened are currently very limited.

"The incident occurred between around 7pm and 7.30pm close to the main car parks of Easton Street at a time when members of the public would have been using the car parks, attending the theatre or preparing for a night out in the town.

"It is therefore very important that anyone who was close to Easton Street at this time and saw something unusual or out of the ordinary or indeed knows anything about this incident gets in touch as soon as possible."

He added: "This is a tragic incident in which a teenage boy has been killed, and I know that it will cause a great deal of concern in the community.

"However, I'd like to reassure everyone that we are carrying out a thorough investigation into what appears to be a targeted attack."

He said there would be a "large police presence" in the area as officers investigated.

Read more UK news:
Attempted murder victim ran into takeaway after stabbing
Boy, 15, charged with murder in Bath city centre
PM 'grateful' to police despite coronation arrests backlash

It comes after three people were stabbed to death in separate incidents in east London over a period of less than eight hours on the eve of the coronation.

A 16-year-old was ambushed as he left school and stabbed to death, while murder investigations were also started after the killings of an 18-year-old and a man in his late 20s, the Metropolitan Police said.

In another incident, an 18-year-old man who has been named by police as Ben Moncrieff was killed in Bath, in Somerset, on Saturday.

Officers were called to the Southgate Street area of the city at around 3.30am on Saturday where the victim was found critically injured and died at the scene.

A man was also stabbed in an attempted murder in Scotland in the early hours of Monday morning.