Woman credited with stopping mass shooting at apartment complex in West Virginia

"She did the right thing. I don't know if any other person would have done that," said Lt. Tony Hazelett with the Charleston Police Department.

Charleston police said it all started when 37-year-old Dennis Butler was speeding up and down a parking lot inside the Vista View apartments.

He was approached by people attending a graduation party and a birthday party, who asked him to slow down, as children were playing.

Witnesses said Butler seemed agitated and left but returned to the complex shortly after, armed with an AR-15 style rifle, and started shooting at the crowd.

Police said a woman pulled out her pistol, shooting and killing him.

"This lady was carrying a lawful firearm," Hazelett said. "A law abiding citizen who stopped the threat of probably 20 or 30 people getting killed. She engaged the threat and stopped it. She didn't run from the threat, she engaged it. Preventing a mass casualty event here in Charleston."

Police said Butler has an extensive criminal history.

In 2016, he was accused of shooting and pistol whipping a 19-year-old woman, but those charges were dismissed because no witnesses testified at a pretrial hearing.

Court records showed Butler had been convicted of two felonies in the past, so he should have not had a gun.

Speaking about the woman, Hazelett said, "She's just a member of the community who was carrying her firearm lawfully, and instead of running from the threat, she engaged with the threat and saved several lives last night."