(NewsNation) — A gunman opened fire inside a suburban Indianapolis mall Sunday, killing three people before being shot dead by a good Samaritan who was armed, police said.

Officers responded to the shooting shortly before 6 p.m. at the Greenwood Park Mall in Greenwood, Indiana, about 15 miles south of Indianapolis. Greenwood Police Chief Jim Ison said the man entered the mall’s food court with a rifle and several magazines of ammunition and began shooting.

Three people were killed in the attack, and two others were sent to area hospitals. One of those wounded is a 12-year-old girl, who Ison said suffered a wound on her back and is expected to recover.

A patron in the mall, a 22-year-old man, shot and killed the gunman, Ison said. The good Samaritan is fully cooperating with police.

At a news conference Sunday evening, Ison said SWAT teams had finished clearing the mall and expected to be on scene through the early Monday morning hours. Police also searched a suspicious backpack found in the mall but said there was no explosive device in it.

Authorities have not yet determined a motive for the shooting and have not released the identity of the shooter, who was male.

“This tragedy hits at the core of our community,” Greenwood Mayor Mark W. Myers said. “Please offer your prayers to the victims and our first responders.”

In a tweet, Indiana Sen. Todd Young called the shooting “terrible news.”

“Praying for the victims of a shooting at the Greenwood Park Mall,” Young said. “Thank you to our law enforcement officers who responded.”

Police will hold another news conference at 2 p.m. Monday Eastern Time to release additional details.