Officers are currently in Headington, Oxford, after a woman was assaulted.
Thames Valley Police was called at 3.10pm today to a report that a woman was stabbed by a man outside the Co-op shop in London Road.
The offender then ran away from the scene in the direction of Stile Road.
The victim was taken by ambulance to the John Radcliffe Hospital with serious injuries.
The offender is described as black, of large build, with short dark hair. He was wearing a green bomber-style jacket with a tracksuit.
Detective Inspector Jim Holmes said: “Enquiries are ongoing in the area to locate the offender. Although we are in the early stages of our investigation, it is believed that the victim is known to the offender.
“People in the community may notice an increased police presence while this is ongoing.
“This incident took place in an area which was busy at the time and I would like to appeal to anyone who was in the area who saw what happened and to anyone who has any dash-cam footage to contact police.”
If anyone recognises someone matching the description of the offender please call police on 999.
If you witnessed the incident or have further information about what happened please call 101, quoting the reference 784 12/3.