Mary Beary was killed on Tuesday night when she was hit by the train at Broxbourne railway station in Hertfordshire at around 10pm.
Ambulance and police crews battled to save the youngster but she was pronounced dead at the scene.
Mary was well known in the Irish traveller community and her death has led to an outpouring of grief.
Caroline Rocky, from Ireland, who is Mary’s second cousin, shared her sympathy to the rest of their family.
Caroline wrote: ‘I just wanted to say sorry to my Uncle Donie, Eileen, cousin Dan and his wife Pamela and her brothers and all the family for the loss of such a beautiful young girl.
God only takes the best.’
Sharyn Ward added: ‘Very sad to hear this. May she rest in peace beautiful angel and praying for her poor mommy and daddy and family.’
For confidential support call the Samaritans on 116123 or visit a local Samaritans branch, or see samaritans.org for details.