A 24-year-old man was arrested after the attack in Sally Port Gardens in Gillingham, Kent, on Tuesday evening.

The stabbing took place near Brompton Barracks, headquarters of the 1 Royal School of Military Engineering Regiment.

Police said the motive for the attack is currently unknown, and added they are "exploring the possibility that it may be mental health-related" and that "a number of knives have been seized".

Sky News understands the attack is not being treated as a terror incident.

Forensic officers have been seen crawling along Sally Port Gardens on their hands and knees as they investigate the attack.

Meanwhile, a forensic officer was seen entering a property on Mooring Road in nearby Rochester, where a man was arrested on suspicion of attempted murder in relation to the attack on the army officer.

Other forensic officers, with sniffer dogs, searched a cordoned-off area of Mooring Road.

One local resident heard a helicopter on Tuesday evening and looked out to see a man having been detained by police.

Another neighbour said he saw a man in handcuffs being led by police into a car.

'Huge scream'

A woman earlier said she heard a "huge scream", ran to her window and saw the attacker stabbing the soldier on the ground near the barracks in Gillingham before escaping on a moped.

Kent Police said the victim - in his 40s - is in a serious but stable condition after being airlifted to hospital.

Another witness said he saw a man in "cream camouflage" motionless on the ground after the attack.

"I came out on the street, went over to the corner. It was a minute and a half after the incident, there were already 10 people around the body," said Alex Reynolds.

"The body was lying there and not moving."

Mr Reynolds and others have described a moped speeding away and someone trying to chase it in a car.

Ring doorbell footage captured shouting and screams, with someone appearing to yell "what are you doing?" and "help".

Attacker 'seemed calm'

A third witness - who didn't want to be named - told Sky News she heard "lots of car horns and men shouting" and assumed it was road rage until she "heard a woman screaming".

"She sounded like a woman who was hysterical. She came this way and said 'my husband's been stabbed, is there a first aider?'"

The witness said the attacker had a helmet on but "seemed calm" and "wasn't even breaking a sweat".

The incident comes 11 years after Lee Rigby was murdered near the Royal Artillery Barracks in Woolwich, southeast London.

The prime minister said he was "shocked and appalled".

Writing on X, Sir Keir Starmer added: "All our thoughts are with the soldier, his family and our Armed Forces community, who serve to keep all of us safe. I wish him a swift recovery."

Mr Starmer also started his first PMQs since becoming the new prime minister by saying how all MPs would have been "shocked" by the incident - and the "thoughts" of everyone were with the officer, his family and those who "serve to keep us safe".

Home Secretary Yvette Cooper said she was getting updates from police.

She said: "This is an appalling attack on a serving soldier.

"I know the whole country's thoughts will be with the soldier and his family and wishing him a speedy recovery.

"This is a live investigation at the moment by Kent Police. I'm being kept updated but I know everyone will want to support Kent Police in their investigation."

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The head of the army, General Sir Roly Walker, said it was a "horrific and unprovoked attack on an officer".

"Our armed forces make extraordinary sacrifices to defend our nation and deserve to be respected," he said.

"My thoughts and best wishes are with him and his family. They have the full support of the chain of command as they recover from this horrendous incident."

Brompton Barracks trains soldiers in construction and engineering skills before their first posting to an operational unit.

It has been the home of the School Of Military Engineering since 1812.