(KTLA) -- A baby girl has died after being found unresponsive by police officers at an Upland condominium complex after the infant's mother threw a toddler from a balcony.
Their mother, 24-year-old Tierra Ortega, was expected to be arrested after receiving treatment for injuries sustained in the incident, which took place in the 600 block of North Wedgewood Avenue around 11:30 a.m. Tuesday, said Capt. Marcelo Blanco of the Upland Police Department.
FOX40 sister station KTLA reports responding officers arrived at the scene and discovered the toddler, a boy about one and a half years old, on the cement beneath the second-story balcony, according to Blanco.
Ortega, who was standing on the balcony when police arrived, then jumped, landing on the ground below, he said. Both the mother and toddler survived and were transported to local hospitals.
Officers went inside the unit, where they discovered the unresponsive baby, believed to be about 6 or 7 months old. She died after being taken to a hospital.
She appeared to have internal injuries and a possible skull fracture, according to Blanco. It was not immediately known when or how she was hurt.
The toddler had a broken foot but was in stable condition, while Ortega is being treated for facial injuries, the captain said.
Ortega was expected to be booked on suspicion of homicide and corporal injury on a child causing great bodily injury upon her release from the hospital, police said.
Blanco described the woman as being around 20 years old and confirmed she was the mother of both children.
The children’s distraught father, who wasn’t home at the time, had raced to the scene, police said.
There’s no history of disturbance calls to the home, investigators said.
Neighbors also told KTLA they'd never noticed anything alarming at the household.
“She was going through something," neighbor Raul Ramos said of the mother. "Who knows? Only God knows.”
Police remained at the scene investigating Tuesday evening; no additional details were immediately released. The motive behind the crime is also unclear.
KTLA's Steve Bien and Jennifer Thang contributed to this story.