Armed police were called after a man who had been shot walked in to Leicester Royal Infirmary and asked to be treated.
The 20-year-old, who had been wounded in the arm, attended the accident and emergency department yesterday afternoon.
Armed officers remained on the scene as a precaution as it was unclear how the man came to be injured and the gunman was still at large.
Later, two men, aged 19 and 22, were arrested in connection with the shooting.
A Leicestershire Police spokeswoman said detectives were hoping the injured man would be able to give a full account of what had happened.
Police said it was unclear where and exactly when the shooting had taken place.
However, Parry Street, off Humberstone Road was cordoned off earlier today as part of the investigation.
Residents said the road was open as usual throughout yesterday.
One said: "It's really bad to hear that a young man has been shot. I hope he makes a full recovery.
"I was here last night and this morning but there was no police cordon here.
"I came back in the afternoon and most of the street was taped off.
"Nobody I know down here knows anything about this boy being shot here."
Another added: "I've lived her for 20 years and there have been some bad crimes, including stabbings, but never a shooting as far as I can remember.
"The police officers down here aren't able to tell us much even though everyone want to know what's going on."
The Leicestershire Police spokeswoman said: "Officers were called to LRI after a man presented himself at the hospital with what were believed to be gunshot wounds.
"In the interests of public safety, firearms officers were deployed to the hospital.
"Two men, aged 19 and 22, have been arrested in connection with the incident.
"They remain in police custody and inquiries are ongoing."
A spokesperson at Leicester's Hospitals said: "We worked with the police when a man presented himself in our emergency department with what was believed to have a gunshot wound.
"In those circumstances we are able to step up security and call for police assistance for the safety of our staff and patients."
"None of this caused disruption to patient care."