A man stabbed to death after being chased through a council estate asked for a blanket as he lay dying in the middle of the road.
The victim, believed to be in his 20s, was stabbed in Brixton, south London, on Thursday evening.
Witnesses said he desperately tried to avoid his attackers but reached a dead-end on Overton Road.
Police have launched a murder investigation after he died on the same night at hospital.
A man, 19, was arrested on suspicion of murder on Friday.
He is being questioned at a police station in south London.
A teaching assistant and mother who lives in the building where the victim was seen running through the corridors said she felt “shocked” and “saddened” by the young loss of life.
Margarida Lopes, 50, said she had seen people fleeing through the corridors for years, often jumping up and over balconies.
She said: “He was conscious and he was asking for a blanket. He was tilting his head up.
“It took a good hour before they took him away so I don’t know if he was severely injured and they were trying to stabilise him before taking him away on the stretcher.
“The tops of his legs were bandaged and he had a wound at the top of his chest towards his shoulder.
Lopes added: “I was so sad to think of this young loss of life and all he had ahead of him. It is such a waste.
“Why would people want to be killing one another?”
Detectives have linked the incident to a car that was found overturned nearby and think it may have crashed into another vehicle before flipping.
The victim has yet to be formally identified but authorities have informed his next of kin of his death.
A post-mortem examination on the body is scheduled on Sunday.