Tokyo police say they received a call about a possible shooting in Machida City, suburban Tokyo, at around 8 p.m. on Friday.
The caller reportedly said that a person appeared to have been shot by a handgun.
Investigative sources say an individual who appeared to be a member of "yakuza" crime syndicates was found unconscious and rushed to a hospital.
An eyewitness told police that two men fled the scene in a passenger car.
The incident occurred in an entertainment district near JR Machida Station.
A worker at a nearby restaurant says that what sounded like gunshots were heard several times at around 8 p.m., and that the gunshots seemed to be getting closer.
The person says that people at the restaurant remained inside until police arrived, and that the incident occurred at a busy time when there are usually many pedestrians.
The person says that people who heard the gunshots were apparently running away.