A machete attacker was pinned to the ground by police after allegedly slashing a McDonald's diner across the face this morning, writes dailymail.co.uk.

The 21-year-old knifeman was arrested on suspicion of murder after he ran into the fast food chain on Sheffield High Street just before 10am - leaving horrified witnesses 'running for their lives'. 

Dramatic photographs show police restraining the attacker who is handcuffed and lying on his front following the attack, which left the restaurant floor covered in blood.

The victim of the attack, 47, is also pictured with a grisly wound on the left side of his face, with blood seeping through thick bandages and on to his navy blue sweater. 

The attacker was spotted by police CCTV operatives minutes before the attack who alerted nearby officer's to the potential attack.

They arrived shortly after the assault and wrestled the machete-wielding attacker to the floor and placed him under arrest. 

South Yorkshire Police say they have arrested the man on suspicion of attempted murder, possession of a bladed article or weapon, and possession of drugs. 

The attack is not thought to be related to terrorism. 

The victim, a 47-year-old man walked out of the restaurant following emergency treatment from paramedics who tended to his gushing wound. 

The large blade was pictured by a witness at the feet of a police officer who was stood near the detained attacker.

Superintendent Paul McCurry of South Yorkshire Police praised the officers who responded quickly.

He said: 'The CCTV operatives in Sheffield spotted a man with a machete, as a result they alerted police on the radio and nearby officers were on scene within less than two minutes of the call.

'They quickly detained the offender, placing the safety of the public over their own without hesitation. This is a superb example of the bravery of police officers who every day do amazing work to protect the public.' 

One witness said on Twitter following the attack: 'In McDonald's in High Street in Sheffield and a bloke just ran in and slashed a guy across the face with a machete.' 

Another described seeing a man 'pouring with blood' following the horrifying attack. 

Another tweeted: 'Some bloke with a machete in Sheffield High Street McDonald's has just been carted off in the riot van.'

A spokesperson for South Yorkshire Police said: 'Officers were called to McDonalds on the High Street, Sheffield at 9:26am this morning following reports of a man with a machete.

'A 21-year-old man was arrested on suspicion of attempted murder, possession of a knife or bladed article and possession of drugs. He is currently in custody awaiting interview. The incident is not believed to be linked to terrorism.

'A 47-year-old man suffered non-life threatening injuries and has been taken to hospital by ambulance.

'Officers remain at the scene, however the High Street remains open.'

MailOnline contacted the McDonald's restaurant where a member of staff refused to comment.