CHICAGO (Xinhua) -- A shooting in a shopping mall in the US Midwestern state of Indiana on Sunday evening left four people dead, including the shooter, and two injured.

The shooting took place at the dining corner of the Greenwood Park Mall, south of Indianapolis, the Indiana capital, at around 6 p.m. local time (2200 GMT).

A man with a rifle and several magazines entered the dining area and started shooting.

Greenwood Police Chief James Eason told a news conference that three people were killed and two wounded.

Police believe an armed bystander killed the gunman at the scene.

The gunman's motive remains unknown.

Indianapolis Police Department Assistant Chief Christopher Bailey said there were "no immediate public safety concerns" for people in the area, according to local media.

Built in 1965, Greenwood Park Mall is the second largest indoor mall in Indiana with about 150 tenants.

Shootings occur frequently in the United States. The Armed Violence Archive's database indicates that there have been 320 mass shootings across the country since the beginning of this year, with nearly 22,500 gun violence deaths recorded.