Schools have beefed up security and police are warning the public amid fears a knifeman who attacked four random victims in London may still be at large.
A 45-year-old woman is fighting for her life and two men in their 20s remain in hospital after a knifeman attacked people walking alone in Edmonton, in the north of the capital, during a 14-hour rampage on Saturday night and Sunday morning.
Schools in the area have brought in extra security today and police have urged anyone walking on their own through the area to take extra care.
Patrols were stepped up as detectives questioned two men, one of whom is in his 40s, on suspicion of GBH after they issued a description of a suspect as a tall, slim black man, possibly wearing a hood.
But investigators are said to be unsure whether either of the men in custody is the knifeman and are therefore encouraging caution from those in the area.
Crime scene: Plumber Roger Blackman (pictured right) helps police officers at the scene of the fourth London stabbing
Police have warned the public to be on their guard following the stabbings in Edmonton from Saturday night into Sunday morning. Pictured: Emergency services attend to the Brettenham Road stab victim
Police are now hunting for the knifeman after four people were stabbed in random attacks during a 12-hour north London rampage
Roger Blackman was first on the scene to the final of the four stabbings and saw the attacker run off, leaving the victim with blood pouring from a wound.
Speaking to MailOnline last night, he said: 'I heard a scream, I looked to my right, I saw a guy run off, then another scream. I saw blood pouring out of the back of him, I went to my van to get some towels to stem the flow.
'I saw the guy turn around and run off, he was literally about 10-15 feet away from where I was. I was in the back of my van so I'm always aware of what's going on around me.
'The victim was screaming, oh my God, oh my God, why has this happened to me. There was blood pouring out of his gash. It was a great big gash, about a three-inch wound.
'I was visiting my mum for mother's day. You hear about it in the papers and now it's happened in front of your mother's house. It does make you wonder, it makes you think about going out.'
The first attack happened around 7pm on Saturday, with a 45-year-old woman stabbed in the back by the man.
She is the most seriously injured and police described her condition as 'critical' this morning.
Forensic investigators collect evidence from the scene of a stabbing in Edmonton after a spate of attacks
