Four dead after a shooter uses a long gun to open fire at an Indiana mall

INDIANAPOLIS (NBC) – Four people are dead, including the shooter, after a man with a long gun opened fire in a mall south of Indianapolis.

Two other victims were also wounded in Sunday’s attack. People inside the Greenwood Park Mall at the time of the shooting say they heard as many as 20 gunshots in the food court.

Authorities said a "good Samaritan" witnessed the shooting and shot and killed the shooter. The gunman is only identified as an adult male at this time. Police say the suspect had a long rifle and several magazines of ammo.

"We have what appears to be one shooter,” said Greenwood Police Department Chief James Ison. “Looks to be an adult male. We have not identified him, yet we don’t have a motive yet. It appears he had a rifle with several magazines of ammunition, entered the food court and started shooting.”

A backpack that police believe was left by the gunman in a bathroom turned out not to be a threat.