(Image source from: Reuters)

A shooting on a downtown Denver street corner on Monday left one person dead and four hospitalized with bullet injuries, as investigators attempt to find at least one suspect still on the loose, a police spokesman said.

The survivors were at first reported to be in serious condition, but police later said in a message on Twitter that the injuries were "believed to be non-life threatening."

No further official details were immediately available about the circumstances of the shooting, which started about 4 p.m. in the lower downtown area of Denver known as LoDo, a district of hotels, restaurants and high-rise residential lofts.

The area is close to Coors Field, home to Major League Baseball's Colorado Rockies.

The Denver Post newspaper cited a witness as saying he saw a single gunman open fire with a pistol on a group of people, then get into the driver's seat of his car, slam the door shut and speed away.

The witness added that he heard roughly six gunshots and that one person in the crowd fired on returned gunfire at the assailant's car as it drove away. The witness also said the people targeted by the gunman appeared to be transients or homeless.

The Denver bloodshed came a short time after an unrelated shooting at a hospital in Chicago, where a gunman killed three, including a doctor, a pharmaceutical assistant, and a police officer before the suspect was himself shot to death, police said.

Related content: 3 Dead Including Police Officer After Shooting at Chicago Hospital

Denver police initially put the total number of victims at four, one declared dead at the scene. Later it updated the toll on Twitter, saying five people were shot, one fatally. The four hospitalized were in stable condition, police said.

There were no arrests and no word on what might have precipitated the violence.

"We don't know right now whether there was one shooter or more than one," Denver police spokesman Doug Schepman told reporters, adding that investigators had yet to determine the cause and whether the assailant or assailants knew any of the victims.

"It's too early to say what happened and why," he added. "To have multiple gunshots fired in an area like this is quite concerning."

Schepman also acknowledged there had been a homicide a couple of blocks away on Sunday, but added, "At this time we do not have information that connects these two incidents."

-Sowmya Sangam