She had been stabbed in the neck.
The teen was taken to the hospital, where she was pronounced dead.
"This is the worst day of my life," Thomas' grandfather Ken Thomas said.
Thomas was a young woman who loved life, according to family and friends. The teen suffered the unthinkable after someone fatally stabbed her in the neck and left her bleeding on the sidewalk, her last words to 911 as she tried to call for help, knowing she was dying.
"When they took her down to the morgue, everyone went into the Church at Interfaith," Ken Thomas said. "I've never seen that before, must have been 50 people there."
The group included many from the Department of Corrections, where Kyanna's mother Anna worked as a Captain.
The family lived in a home in Rosedale, Queens.
Anna is separated, and her husband lives just a few blocks away with Kyanna's younger brother Kyle.
Jordan Buddoo went to elementary school with Kyanna and just saw her on Friday.
"All of a sudden I hear one of my good friends is dead," Buddoo said. "She was a beautiful young girl. I really enjoyed her company a lot. It's just a shame that's she's gone."
Relatives say she was spending the weekend at her aunt's home.
"She was in the bed sleeping, and the last time they saw her was around 10:30, 11 p.m.," Ken Thoams said. "And I guess somebody called her and she slipped out the house."
Then, she crossed paths with her killer.
"I used to tell her, you've got to be careful out there," Ken Thomas said. "And she'd say nobody's going to bother me, you know."
So far, no arrests have been made. The investigation continues.