A spokesperson for the St. Louis Metropolitan Police Department said a St. Louis, MO armed citizen was forced to draw his gun on his own brother in order to stop a violent attack shortly before midnight Thursday.

According to authorities, the 56-year old man was in a Skinker DeBaliviere neighborhood home along with his brother and his brother’s girlfriend when something happened between the three which caused his brother to become extremely angry with the woman.

When police arrived at the scene, they found 48-year old Gary Peters suffering from a gunshot wound to the stomach. Peters was taken to the hospital but was pronounced dead a short time later.

Peters’ girlfriend told police after he started to attack her with a hammer, his brother stepped in to stop the violent beating. But the woman said Peters turned his aggression and the blunt object on his own brother. That’s when his brother was forced to retrieve his handgun.

The woman was treated for blunt force trauma injuries to the head and said to be in stable condition following the attack.

Police said no charges have been filed and the incident is still under investigation.