A family have paid tribute to their "adventurous" and "beautiful" 13-year-old daughter after she was found dead on railway tracks.
Zoe Miller's body was found on train tracks near Berkhamsted rail station in Hertfordshire early on Monday morning.
It is thought the teenager might have fallen to her death from a road bridge, British Transport Police (BTP) said.
Her parents Jane and Rob Miller described her as a "brilliant and creative" girl who had "an amazing life ahead of her".
It is thought Zoe slipped out of the family home late on Sunday night because she could not sleep and climbed the wall on to the bridge over the rail tracks behind her house.
In a statement, Mr and Mrs Miller said they thought Zoe was "just messing around and did not perceive what would happen", having packed her bag for school, done her homework, laid out her school uniform, organised plans for future events - and left no note.
"It was a terrible accident and we are still trying to come to terms with the situation."
Paying tribute to their daughter, who was pronounced dead at the scene by paramedics, they said: "Zoe was an adventurous, brilliant, creative, beautiful, happy and wonderful daughter and we are trying to come to terms with our loss."
British Transport Police are urging members of the public to contact them to help them piece together the teenager's final moments, although the death is not being treated as suspicious.
A BTP spokesman said an inquest into the teenager's death is due to be opened and adjourned on Thursday and confirmed that Zoe had not been struck by a train and was found by ground staff with burn injuries, thought to have been caused by overhead wires during the fall.