An 18-year-old man was taken to hospital after allegedly being stabbed in Grantham on Friday morning, but the extent of his injuries are currently unknown.
Lincolnshire Police were called to Swinegate at 11.42am on February 5 and said the man was found with injuries consistent with a knife wound.
Police were seen walking around the front of a nearby church and carrying out forensics work in a coned off area. No arrests have been made by the time of publication.
An air ambulance was also spotted in Grantham at a similar time, but it is not yet known if this is connected to the same incident.
Anyone with information, or who witnessed the incident, should contact police on 101 quoting incident 129 of February 5.