OXON HILL, Md. (AP) — Prince George’s County police say a man stabbed his girlfriend’s two teenage sons when they tried to protect her from him. One son, a 14-year-old, was killed.

Officers called to the Oxon Hill apartment early Monday found 14-year-old Keyshaun Mason and his 18-year-old brother suffering from stab wounds.

READ MORE: 'Tactless Finger Pointing': Baltimore Officials Push Back On Hogan's Criticisms Of The City During 'Re-Fund The Police' Announcement

Authorities say 48-year-old Sean Crawford, the live-in boyfriend, had been arguing with her, and Mason and his brother tried to help her.

Police say Crawford grabbed a kitchen knife and barricaded himself and the teens’ mother in a bedroom. Officers say when the youths forced their way in, Crawford stabbed Mason in the chest and the other brother in the shoulder.

READ MORE: Baltimore County Public Schools Feeling The Impact Of Nationwide Teacher Shortage

Authorities say Mason died at Children’s Hospital. The other brother was taken to another hospital.

Crawford is charged with murder.

MORE NEWS: Ravens CB Marlon Humphrey To Speak At Graduation Ceremony For People Who Completed Drug Treatment

(Copyright 2015 by The Associated Press. All Rights Reserved.)