"There were words between the two of them, and one of them went and grabbed a knife," Fort Worth Police Department spokesman Bradley Perez told the newspaper.
The 13-year-old fled the scene and was at large overnight, according to WFAA in Dallas. She was arrested Wednesday at her home.
Authorities said the stabbing took place during a sleepover, but Lightfoot's mother, Anntoinette Carter, said that was not the case. Carter told the Star-Telegram outside juvenile court Thursday that the argument started when the 13-year-old girl asked to sleep over and Carter said no.
The girl texted Lightfoot to come to her apartment to pick up some clothes she had left there, and that’s when the fight turned physical, Carter said. The 13-year-old went back into the apartment and returned with a knife, she said.
Police officials have offered no further details of what took place.
"Now I'm daughterless," a tearful Carter told the newspaper. "And my heart feels like it's just been ripped out and just stomped on."
Carter said in the interview that the girl’s mother watched the fight prior to the stabbing and did nothing to stop it.
The suspect's mother, who was at her daughter's initial court appearance Thursday, declined to give the Star-Telegram a statement.
"The truth will come out," she said as she walked away from reporters.
See Carter’s interview with the Star-Telegram below.
Carter described her daughter as the “sweetest little girl here.”
"She didn't bother nobody," she told the Star-Telegram. "She made straight As. She was friends with everybody."
Lightfoot’s grandfather, Dwight Roberts, said he wants justice for his granddaughter, whatever form it might take.
"This is just a wake-up call for everybody," Roberts said. "Not only my grandkids, but other kids. When your parents tell you not to do something, don't do it. Just wait. Live another day."