Armed police descended on a busy road in east London after a still-at-large "lunatic" attacker stabbed a man and chased him down the street.
Witnesses said the broad-daylight attack in Dagenham Heathway on Monday (2 October) saw the victim scream as he tried to run from the blood-stained attacker.
Elena Rogers, who was walking down the road with her partner, told the Barking and Dagenham Post: "The attacker was so brazen – he didn't even care that everyone could see him. The man's a lunatic.
"The one who had been stabbed was screaming and you could tell he was in agony. It shook me up a bit.
"I'm only glad I didn't have my children with me."
The victim, believed to be aged in his 40s, was later found by emergency workers with stab wounds and taken to hospital. There has been no update on his condition.
The suspect is still at large and no arrests have been made.
Police say they were first called at around 1.05pm to reports of a stabbing and a man seen in possession of a firearm.
There was no evidence of shots fired, officers added.
Detectives believe the victim was attacked following "an incident" in nearby Sterry Road.
Police and ambulance vehicles were seen outside Iceland and Lidl supermarkets opposite Dagenham Heathway Tube station, with cordons closing entrances to both stores.
A spokesperson for the Met Police said enquiries continue.