A baby girl died in The Bronx today, authorities said.
Her 15-year-old sister went to check on 3-month-old Fiona Hern shortly before 10:30 a.m. in their Castle Hill apartment on Lafayette Avenue, but found her not breathing, police sources said.
Her mother had put the baby to sleep at 2 a.m.
The sister called out to the mother, who began giving the baby CPR while waiting for police to arrive, sources said.
EMS rushed Hern to Jacobi Hospital, but she was pronounced dead at 10:55 a.m., cops said.
No criminality is suspected at this time, but the medical examiner will determine the cause of death.