A medical emergency resulted in a young girl being declared dead when her flight landed at Los Angeles International Airport Thursday night, authorities said. Delta Flight #2423 on its way to Seattle returned to LAX due to a passenger medical issue on board, according to FAA spokesman Ian Gregor. The passenger was a 10-year-old girl suffering a cardiac arrest on the plane, according to CNN affiliate KTLA. “LAFD paramedics responded to a medical aid for a minor female child and furiously worked to save her life. Sadly, all efforts were futile and the child was beyond medical help,” the Los Angeles Fire Department said in a statement. The Los Angeles County Coroner’s office is investigating the passenger’s death. Delta airlines confirmed the incident and said the company is working to re-accommodate customers that were on the flight.