A hospital was put on lockdown after a nurse was stabbed.
The attack happened at the Ailsa Hospital car park in Ayr shortly after 10am on Thursday.
Staff and patients were locked in rooms while the attacker, who was a female patient, is still being hunted.
A woman is in a serious but stable condition in hospital. Her relatives have been made aware.
Officers deployed a police helicopter following the attack.
The hospital is now open as normal.
Superintendent Brian Shaw said: "I am urging anyone who witnessed the attack to get in touch with us.
"I am particularly keen to hear from anyone who was in the area around 10am and has information about a woman who was seen leaving the area shortly after the 42-year-old woman was stabbed.
"She is described as being around 5ft 2in to 5ft 3in in height, slight build and pale complexion. She was wearing a dark woolly hat and a dark jacket.
"If you recognise her description or have information about her identity please call Police Scotland via 101.
"Information can also be given anonymously to Crimestoppers on 0800 555 111. Incident 0923 of 22 November 2018.
"It is important that the public is aware that the hospital is open as normal.
"Officers remain at the hospital and we have increased high-visibility patrols in the area to reassure patients, staff and the wider public."
"Officers are reviewing CCTV and carrying out door-to-door enquiries in the area in an effort to identify the woman responsible."
Speaking at First Minister's Questions on Thursday, Nicola Sturgeon said: "I was receiving reports about this incident just as I came into the chamber.
"Our understanding is that injuries sustained by a nurse are not life-threatening injuries and that police are fully involved in this incident.
"Obviously, the safety of staff an patients is of the utmost importance."