Before she was killed and her 5-year-old son injured in a shootout with Baltimore County police, Korryn Gaines was live-streaming the standoff to the Internet. Her social-media followers, police said, were encouraging her not to give in.

She did not. After repeatedly pointing a shotgun at officers standing in the hallway of her Randallstown home Monday over hours of negotiation, police said, Gaines told them to retreat or die.

"If you don't leave, I'm going to kill you. I'm going to kill you," she said at about 3 p.m., according to Baltimore County Police Chief James W. Johnson at a news conference Tuesday.

Police said they fired a shot, and Gaines responded with a barrage of gunfire. They shot three more times. Gaines was killed. Her son, hit by a bullet or shrapnel, is still in the hospital.

Amid the negotiations, police authorities successfully petitioned Facebook to disable the 23-year-old's accounts, which took about an hour to take effect.

Police arrived at Gaines's home that morning to serve an outstanding warrant from another encounter she had recorded and shown online: a March traffic stop that ended in her being charged with disorderly conduct and resisting arrest. Police also had a warrant for her boyfriend, Kareem Kiean Courtney, 39, who was charged with second-degree assault in a domestic incident involving Gaines.

No one answered the door, the chief said in recounting events. Courtney soon came out of the residence with a younger child and was arrested on the assault warrant. He was later released on his own recognizance.

But Gaines refused to leave, police officials said. When officers entered using a landlord's key, they said, Gaines was sitting on the floor pointing a shotgun at them, and her son was nearby.

Police retreated to the hallway and began an "hours-long dialogue" with Gaines, Johnson said. Trained negotiators, mental health counselors and Gaines's father all were summoned to talk her out of the apartment.