A man who had serious stomach and neck injuries after an attack is in a stable condition in hospital, police said.
The victim, 38, was found in the Old Village area of Corby at about 20:35 GMT on Saturday and taken to hospital.
Northamptonshire Police said they had been searching the area and appealed for information, but no arrests had been made.
Photos shared on Twitter by the force show police examining drains and the roof of a building.
Police did not reveal how the victim's injuries were inflicted, or if they were searching for a weapon.
Det Insp Dave Harley, said: "Our officers are working around the clock to find those responsible for this attack and we are working on a number of lines of inquiry."