Suffolk County police say that a 13-year-old boy saved his mother from a "violent and potentially fatal attack" when the boy stabbed his mother's ex-boyfriend in their Mastic Beach home on Monday.

The incident happened at 3:45 a.m., when Norman Shields, 48, entered the home and got into a fight with his ex, Natasha Bivens, 31. (Shields and Bivens have a four-year-old girl.) According to police, "An armed intruder, who turned out to be an ex-boyfriend of a female occupant of the house, entered the home and engaged in a physical confrontation with the female victim and her new boyfriend."

Bivens tried to stop Shields from entering a bedroom. Newsday reports, "Shields fired one shot from the revolver he was carrying, but no one was struck by the bullet, [Det. Lt. Jack] Fitzpatrick said. At that point, the son, whose name was not made public, stabbed Shields several times on the left side of his body with a kitchen knife... Bivens' current boyfriend fled the house at some point, Fitzpatrick said."

Shields, who had an extensive criminal record, died at Brookhaven Memorial Hospital Center.