At least four people, including the shooter, are dead and others are injured following a shooting at a shopping mall in the suburbs of Indianapolis, according to local reports. 

Greenwood Chief James Ison said "a good Samaritan with a handgun" at the scene killed the shooter. He said two others were wounded and are being treated in area hospitals. 

Investigators on the scene of the crime. (Facebook/@Ty J S)

The shooter has only been described as an adult male. Police said he had a rifle and several magazines of ammunition.

A shooting at a mall in Greenwood, Indiana, on Sunday evening has left at least four people dead, including the suspected gunman — who police say was shot by an armed bystander.

The latest: Authorities said a 12-year-old girl was among two people wounded after the shooter opened fire with a long gun at the mall, south of Indianapolis. Her injuries were minor, Greenwood Mayor Mark Myers said in a statement.

A shooting rampage that killed three people and injured two others at an Indiana mall ended after an armed witness shot and killed the assailant, police said.

Around 6 p.m. local time Sunday, multiple people called 911 to report an active shooter at the Greenwood Park Mall, Greenwood Police Chief Jim Ison told reporters.

Investigators believe the unidentified gunman, an adult man, was shot and killed by a lawfully armed 22-year-old man who "observed the shooting in progress," Ison said.