Three people, including two children, were taken to hospital following an early morning attack by a knifeman who then set fire to a house in England, witnesses said.
A young woman is said to have run across a road naked and screaming while being pursued by a man who stabbed her several times.
A girl and boy were also caught up in the commotion in Albion Road, Broadstairs, Kent, at 7.50am.
One child suffered minor injuries and the other was taken to hospital as a precaution.
Passer-by Jeremy Talbot, 29, told how he stumbled upon the incident on his way to work. He went to the badly injured woman's aid before seeing smoke coming from a nearby house.
After being told that children may be inside, mechanic Mr Talbot rushed to the building. He was then told that the youngsters were outside the property.
Father-of-two Mr Talbot, from Ramsgate, said: "I was on my way to work and there was a crowd of people in the middle of the road.
"Someone came up to me and said, 'You can't come up, someone's been stabbed'. I then grabbed my first aid out of the boot and went over."
Mr Talbot described how he tended the injured woman, who was covered in blankets, to try to treat her wounds on her neck and back. She was later taken to a hospital in London.
"It was just adrenalin kicking in," Mr Talbot said. "I'm not a hero. All I did was what any other normal person would have done."
A man who is believed to be known to the victims was arrested as investigators sealed off the scene. Kent Police have said they are not looking for anyone else. Firefighters were sent to extinguish the blaze.
On Facebook, Mr Talbot's wife Sally Jane Talbot gave her account of what she and her husband saw en route to dropping him off at work and one of their children at nursery.
She wrote: "She just ran across the road naked and screaming and the bloke followed with a knife and stabbed her several times, including a really bad one in the neck."
Mrs Talbot described how the man stabbed the girl in the hand, adding: "He then went in the house and set it alight. My hubby was doing first aid on the woman when the bloke set fire to the house and someone said there were children inside.
"So hubby kicked the door down and went in to get them. The bloke with the knife then went to the door and a neighbour pushed him back so hubby could get in. Then they said the kids were out of the house, so they came back out."
A police spokesman said: "At 7.50am on Wednesday September 21, Kent Police was called to an assault at Albion Road, Broadstairs.
"Police officers are currently at the scene where three people have sustained injuries. Albion Road is closed at its junctions with Sowell Street and Church Street.
"South East Coast Ambulance Service has attended and three people have been taken to hospital."