An unidentified gunman calmly shot dead a man and badly injured a woman outside a Paris hospital on Monday before fleeing the scene on a scooter, police and witnesses said.

Officials ruled out a terrorist attack, with witness statements appearing to point to a targeted killing.

Images of Parisian hospital, scene of fatal shooting Images of Parisian hospital, scene of fatal shooting Photo: AFPTV / Aurelia MOUSSLY

"It really looked like a mafia execution, like in a film," the owner of a cafe opposite the hospital told AFP, requesting that his name be given only as Arnaud.

The attacker fired several shots at the Henry Dunant private geriatric hospital run by the Red Cross in the upmarket 16th district, investigators said.

"One person died and one is seriously injured," a fire service source said.

Police cordon off the area outside Paris' Henry Dunant hospital after a fatal shooting Police cordon off the area outside Paris' Henry Dunant hospital after a fatal shooting Photo: AFP / Anne-Christine POUJOULAT

"It's probably a settling of scores," a source close to the investigation told AFP.

Another source close to inquiry said the dead man was born in 1987 and "very well-known notably for murder, drug trafficking and criminal association".

The two casualties were taken into the hospital after the early afternoon shooting. The man died from his wounds.

The attack happened in the well-heeled 16th district of the capital The attack happened in the well-heeled 16th district of the capital Photo: AFP / Anne-Christine POUJOULAT

"I heard six loud shots while I was having lunch around 1.30 pm (1130 GMT)," the caretaker of a nearby building told AFP.

"I went out immediately, and I saw a young black man on the ground, face down, outside the hospital.

"He was maybe 20 or 30 years old and he was already dead," said the caretaker, who declined to give her name.

A map locating Henry Dunant hospital in Paris A map locating Henry Dunant hospital in Paris Photo: AFP / Tupac POINTU

The injured woman works as a security guard at the hospital, which runs a Covid-19 vaccination centre. Prosecutors said late Monday that she was in a serious condition and her prognosis remained uncertain.

Prosecutors said they were treating the shooting as a murder and an attempted murder.

District mayor Francis Szpiner told reporters that the attacker had fired several rounds at the man.

A map locating Henry Dunant hospital in Paris A map locating Henry Dunant hospital in Paris Photo: AFP / Tupac POINTU

"It would seem that the security guard was hit by a stray bullet," he said.

Szpiner said the shooting was "neither a terrorist attack nor an attack on the vaccination centre".

The owner of a restaurant across the street from the hospital told the BFMTV television channel that he also heard shots ringing out.

"I turned around and I saw a guy with a hoodie firing. Then I saw him approach a guy lying on the ground and put two bullets in his head to finish him off," he said.

"The shooter walked off with amazing calmness, as if nothing had happened," he said.

Aboubakar Fofana, the restaurant's chef, said he had seen the shooter "climb onto a grey X-Max scooter that was waiting for him".

"The driver was quite large, while the shooter was rather tall and athletic," Fofana said.

"The whole time he walked calmly -- he was completely impassive, as if he was going to buy a cup of coffee," he told AFP.

Police cordoned off the area around the hospital, and forensic experts were examining the scene for clues, AFP journalists said.

After the attack, the hospital turned away several people who had been waiting for doctors' appointments, admitting only priority patients.

"The hospital is now functioning with reduced staff," a Red Cross staffer told AFP. "There are a lot of people in shock inside."