Police sealed off a street in Glenrothes on Monday evening following a incident in the Tanshall area of the town.
Witnesses report seeing a number of police vehicles, as well as an ambulance, in the Cullen Drive area at around 6.30pm on Monday.
An area of Cullen Drive was taped off as an investigation got under way.
Both uniformed and plain clothed officers were seen doing door to door enquiries.
Officers carried out a search of Cullen Drive, made up of a number of adjoining cul-de-sacs.
White-suited forensics officers attended while a number of officers manned the cordon.
One resident said police swooped on the area in large numbers on Monday evening.
They said: “Very quickly there were at least six vans and police cars which seemed to appear from nowhere.
“It’s shocking to see such a large police presence.
“Then they started taping off several sections of Cullen Drive.
“It became apparent very quickly that it was a serious incident.
“Then forensics officers turned up as officers continued to search several parts of the area.”
The resident also confirmed that officers had also been conducting house-to-house enquiries throughout Cullen Drive as a police investigation got underway.
A Police Scotland spokesperson said: “Officers were called to Cullen Drive in Glenrothes at around 4.20pm on Monday July 26 after a man was found seriously injured.
“The 40-year-old was taken to hospital for treatment.
“A man has been arrested in connection with the incident and enquiries remain ongoing.”