A Florida mother is accused of fatally stabbing her 11-year-old daughter 15 times to prevent her from having sex with her daughter’s grandmother’s boyfriend.

Authorities arrested Rosa Rivera, 28, on Sunday in Orlando after she arrived at the Winnie Palmer Hospital for Women & Babies carrying the body of her daughter, Aleyda Rivera, in her car’s passenger seat, WOFL reported.

Sheriff’s officials say Rivera requested medical assistance for her child at the valet parking area for the hospital. Aleyda, who suffered from 15 stab wounds, was declared dead at the scene, officials said.

Police officers dispatched to the scene described Rivera as being “argumentative” before threatening them with a blood-stained knife, officials said.

Orlando Police Department spokesperson Lt. Diego Toruno said the hospital had to go on lockdown briefly because of the incident.

Hospital security and law enforcement detained Rivera before arresting her on one count of first-degree murder.

Rivera allegedly confessed to murdering her daughter, telling authorities she stabbed her daughter while in the car because she was sexually active.

The woman told authorities she thought her daughter was sexually active because she “smiled different” even though she never walked in on her having sexual relations with a man.

“Rosa Rivera killed her daughter because she wanted to prevent her from having sexual relations with men,” Sheriff John Mina told WFTV on Monday. “But we believe that part of the investigation is unfounded.”

“We believe the stabbing actually happened in the vehicle,” Mina added. “She did drive her around in the car, and at some point, when she was in the car, Aleyda passed.”