Armed police arrived at Westmuir Street, Parkhead, Glasgow, shortly after 1pm yesterday.
It is understood the victim was targeted while working in a block of tenement flats for City Technical Services.
Witnesses said he was standing in the close when the gunman burst in and shot him in the shoulder.
His condition is not known but his injuries are thought to be not life-threatening.
One neighbour said: "The guy was working in the close of the building when he got shot.
"I didn't hear a thing, then suddenly there were police with guns all over the street."
Police were guarding the main door of the property, as detectives carried out enquiries.
Around two hours after the suspected shooting, forensic officers arrived at the scene.
Officers also carried a finger-tip search of the pavement outside the tenement building.
Locals gathered at the cordon yesterday afternoon.
As parents collected their children from the nearby school and nursery, shortly after 3pm, some expressed their shock at the daylight incident.
A Police Scotland spokeswoman, said: "We can confirm a man was taken to hospital with a suspected gunshot wound following an incident in Westmuir Street.
"The incident was reported to police at 1.10pm. Inquires are continuing."