A teenage girl has died after she was discovered unresponsive at a home in Elanora Heights, a suburb on Sydney's Northern Beaches. Emergency services were alerted to a concern for welfare at the residence around 5:45 p.m. on Sunday. Paramedics provided treatment at the scene before the 16-year-old was airlifted to Royal North Shore Hospital in critical condition. NSW Police confirmed on Tuesday night that the teenager had died in hospital. An investigation into the circumstances surrounding her death is underway, and inquiries are ongoing.