Residents in north London where four people were « randomly » stabbed within 10 hours have been told to be vigilant despite two arrests being made.

Two people are still in a critical condition in hospital following the attacks in Edmonton over the weekend.

Det Supt Luke Marks said people should « remain vigilant, especially when walking alone ».

A nearby grammar school has put a « lock-down procedure » in place as a « precautionary » measure.

In an email to parents, head teacher of the Latymer School Maureen Cobbett said students would not be allowed to leave the school during breaks and lunchtime, and after-school activities would not take place « until further notice ». Police believe the four people attacked, who were all stabbed in the back, had been selected randomly.

The first victim, a 45-year-old woman, remains in a critical condition after she was attacked in Aberdeen Road at 19:02 GMT on Saturday.

Four hours later, a 52-year-old man was stabbed half a mile away in Park Avenue. He has since been discharged from hospital.

The next victim, a 23-year-old man, is in a critical condition after being attacked near Seven Sisters Tube station at about 04:00 BST on Sunday.

The final stabbing happened at 09:42 in Brettenham Road where a 29-year-old man was attacked. He is receiving medical treatment but his injuries are not life-threatening. Two men are in custody after being arrested on suspicion of causing grievous bodily harm.

One was held in Fore Street, Edmonton, on Sunday morning while a man aged in his 40s was arrested at a residential address at about 19:00.

Det Supt Marks said police still « believe that a single suspect was involved » and inquiries were ongoing, although the attacks were not thought to be terror-related. The suspect has been described as a slim black man, who is about 6ft 3in tall and was wearing dark clothing.

The Met previously said they thought « mental health issues may be a factor » and extra police patrols had been put in place « to keep the public safe and catch the individual responsible ».