Neighbors say it could have been much worse.

An unnamed "good guy with a gun" put a stop to what could have been a horrific mass killing over the weekend by using his own weapon to gun down a massacre suspect, KFSM-TV reported. What are the details?

Authorities said an armed 26-year-old Zachary Arnold, a resident at the Fort Smith, Arkansas, apartment complex where the event occurred, was outside his building Saturday morning when he began screaming for residents to come outside.

Arnold, who was armed with a rifle, was first met by an elderly neighbor, 87-year-old Lois Hicks.

One neighbor told the station that Hicks and another elderly woman came out to "console" Arnold when he opened fire.

"There were two older women, both had come out," the neighbor explained. "One of them had ran back in, and the other one ran back in, but she didn't close her door, then he walked in and did what he did."