Hannah was 15 years old. Police and paramedics were called a disused viaduct in Tavistock on Saturday afternoon where they found Hannah and a 14 year old boy.
Police officers think the pair had an adverse reaction to the unknown substance which police found at the scene.
Hannah was pronounced dead shortly after reaching hospital; Hannah and the boy were airlifted to Derriford Hospital where he is now in a stable condition. College friends left tributes of flowers and balloons and comforted each other at the scene.
One card left on the path leading to the scene said: “To the most beautiful angel in the sky, me and Harry will miss you so much. Harry will grow up knowing his auntie was a beautiful kind-hearted girl.”
Sarah Jones, the principal of Tavistock College which Hannah attended, said the college was in mourning following the death of Hannah who was a year ten student.
Principal Jones said: “The loss of this young lady will impact on all of us in many ways. She was a lovely, caring, talented and popular student who will be missed by everyone who knew her.
‘Always seen about school with a smile on her face, she had everything to live for. Her friends are grief-stricken that she should be taken at such a young age.”
Students were being offered support if they need it by School Pastors and the Revd Christopher Hardwick the Vicar of Tavistock.
Catherine O’Boyle the coach of Tavistock Girls Rugby team said: “Hannah was an incredible member of our team and the whole club. She was so dedicated to the sport and to her team mates.
‘She was such a calming and positive force within the team, on and off the pitch.”
A special assembly was held at Tavistock School for Hannah on Monday.