Two teenagers have been arrested after a man was killed in a 'random, unprovoked attack' at a fair in Maryland.

Witnesses described how the victim was 'minding his own business' when he was 'sucker punched', allegedly by high school students, and left lying unconscious on the fairground.

The victim, identified today as 59-year-old John Weed, was taken to a shock trauma center in Baltimore where he died the following day.

The two suspects, aged 15 and 16, were arrested on Friday after witnesses at the Great Frederick Fair in Frederick, Maryland, told detectives what had happened.

A Frederick County Sheriff's Office stand at the Great Frederick Fair in Maryland where police were forced to respond to a violent attack that led to a man's death

Sources told WJLA that the pair may have been playing a sinister 'knockout game' in which people try to knock random victims unconscious.

The theory would 'certainly be looked at', the sheriff's office said.

According to a transcript of police radio traffic, the man's collapse was initially reported as a heart attack before it became clear he had been attacked.

'We're getting reports these were students who sucker punched somebody and they were out cold,' one deputy said.

Organizers of the Great Frederick Fair insisted it was an 'isolated incident' and said no weapons were used.

The victim was found unconscious shortly after 5.30pm on Friday, police said.

He was hurriedly flown to Baltimore to be treated at the R Adams Cowley Shock Trauma Center.

On Saturday afternoon medics informed police that the man had died of his injuries.

'Criminal investigators responded to the scene and interviewed numerous witnesses who indicated that the person assaulted was the victim of an unprovoked attack,' police said in a statement.

'As a result of the investigation, two juvenile suspects were able to be identified and were later located and arrested by the Sheriff's Office.'

The 15-year-old, a black male, was charged with first and second degree assault and reckless endangerment.

The second suspect, aged 16 and also a black male, was charged with second degree assault.

Police said a 59-year-old man had been found unconscious and was taken to hospital in Baltimore. He later died of his injuries

The Sheriff's Office is now consulting with attorneys over whether they will face additional charges such as murder or manslaughter.

The victim's body has been transferred to the State Medical Examiner's Office for an autopsy.

Fair organizers said: 'The Great Frederick Fair's number one priority is the safety and security of our guests.

'To dispel rumors of the events of last night, while there was an assault, there was NO shooting and NO stabbing.

'The team of security and law enforcement was able to respond rapidly to control and contain the incident.

'The investigation into this incident remains active and any further information regarding the assault will be released from the Sheriff's Office.'

Anyone with information is urged to contact Detective Jen Skelley at 301-600-1046, or the police tip line at 301-600-4131.