A nurse is in a serious condition in hospital after reportedly being stabbed by a patient.
The alarm was raised about the incident at Ailsa Hospital in Ayr at around 10.05am on Thursday.
Officers are carrying out an "extensive search of the local area".
The nurse was taken to Ayr hospital and is in a "serious but stable" condition, Police Scotland said, adding that her family had been informed.
Speaking at First Minister's Questions, MSP for Ayr, John Scott, said: "I understand a nurse has been stabbed by a patient".
First Minister Nicola Sturgeon said the woman's life was not believed to be at risk, and she would be getting a "full update" as soon as she left the chamber.
University Hospital Ayr and Ailsa Hospital are no longer on lockdown.
Movement around the site can be now be resumed, with the exception of the courtyard car park in front of Addictions Services.
— NHS Ayrshire & Arran (@NHSaaa) November 22, 2018
Earlier, NHS Ayrshire and Arran tweeted that the hospital was "on lockdown and no members of staff, patients or visitors will be able to leave the site until advised".
In a later update, it said that "movement around the site can now be resumed, with the exception of the courtyard car park in front of addictions services".
Police said an "area of car park and (an) adjacent building (had been) secured for examination".
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Billy McClean, from the local health board, said staff were "assisting Police Scotland with their investigations".