A young teacher is fighting for her life after being stabbed in the neck as she pushed her 21-month-old son in his buggy in Surrey.
Abigail Witchalls received a single stab wound to the neck
Abigail Witchalls, 26, was attacked on Wednesday afternoon in Burnhams Road, a residential area of Little Bookham.
She was taken to a hospital in London where she was described as being in a critical condition on Thursday.
Officers said it took them some time to establish what happened, leading to an 18-hour wait before an appeal was made.
Surrey Police believe Mrs Witchalls was attacked by a man who had approached her, demanded money, and then stabbed her once in the neck as she screamed for help.
Officers have searched a large area for a weapon but said nothing had been found.
The only description police have given of the attacker was that he was a white man.
Mrs Witchalls, who works part-time teaching English to immigrant women, is being treated at St George's Hospital in Tooting.
Her husband Ben is by her side, while their son Joseph is being cared for by relatives, police said.
Ch Supt Rob Price said: "It's difficult to tell in terms of the psychological impact but the child is unharmed.
"This is obviously a very quiet, suburban, affluent area. This type of incident is very, very rare indeed.
'Should not panic'
"This is the lowest serious crime area in Surrey which has the lowest serious crime in England and Wales."
Police said people in the area should not panic and there should not be "additional concern".
Officers have appealed for information from anyone in the area at the time.
They are particularly keen to speak to anyone who saw or heard anything suspicious in the area of Little Bookham Street, Oakenwood and Burnhams Road between 1530 and 1700 BST.
Surrey Police also issued a statement explaining why it had taken 18 hours to issue an appeal for help at a time an attacker was at large.
It read: "It took some time yesterday evening to establish exactly what had happened.
"Bearing in mind that nobody had actually seen the incident take place, before going out with an appeal that would alarm the public we wanted to make sure that we had the facts absolutely correct."