Thames Valley Police officers are in the area of Marlborough Street in Milton Keynes.
It’s after the force received a report shortly before 3pm today that a 15-year-old girl was taken ill.
She was treated by paramedics from South Central Ambulance Service, but has sadly since died.
The death is being treated as unexplained and investigations into the circumstances are under way.
Officer say you may notice an increased police presence in the area while investigations continue.
The girl’s next of kin have been informed and are being supported by specialist officers.