St. Louis police were called to the scene of a shooting around 11:30 p.m. Monday, and when they arrived at a residence in the 4500 block of Alcott Avenue, they found a man suffering from gunshot wounds near the home's entrance, the St. Louis Post-Dispatch reported.

The wounded man was taken to a hospital where he was pronounced dead, the paper said.

Soon after police found a 40-year-old man they believed was the shooter, and he had a gunshot wound to his hand courtesy of his own gun, the Post-Dispatch added.

What happened next?

Police told the paper the shooter was in stable condition, and that he said the now-deceased man entered his home and attempted to assault him.

But it turns out this guy also had a gun to help him out of this jam — and he put it to use in his time of need. The Post-Dispatch said the man opened fire.

With that, police arrested the shooter Tuesday and sought charges from the St. Louis Circuit Attorney's Office, the paper added.

A subsequent Post-Dispatch story identified the fatally shot man as 58-year-old Michael Norman who lived in the 1100 block of Belrue Avenue in University City.

The paper said in the follow-up story that the 40-year-old shooter was arrested on suspicion of second-degree murder and armed criminal action.

Here's video showing the aftermath of the shooting:

But prosectors won't file charges

However, St. Louis prosecutors declined to file murder charges against the shooter, citing self-defense, the Post-Dispatch said.

The paper said a spokeswoman for the circuit attorney could not be reached for comment Wednesday.

The Post-Dispatch said it isn't identifying the shooter because he was not charged.