A 16-year-old boy was killed almost instantly when he was hit by a high speed train while running away from police, an inquest has heard.
One officer shouted "Get off the tracks!" to warn Mitchell Rodgers the train was passing through Belper station in Derbyshire, jurors heard.
They did not see the train hit Mitchell but one officer said he saw "a large area of red" after the collision on 28 March 2015.
His cause of death was head injuries.
The inquest heard how Mitchell's body was located using heat detection equipment on the police helicopter.
PC David Chambers, the officer who started chasing Mitchell, gave evidence at the inquest in Derby.
"It's always a difficult decision to make whether to chase or not," he said.
"My experience told me on balance to pursue."
The inquest heard that Mitchell, from Nether Heage, had been drinking on the night of his death.
Police were responding to a 999 call about an altercation involving a group of youths in the town.
PC Chambers, who is now retired, told the jury that he spoke to Mitchell, who "wasn't obstructive" but all of a sudden "turned round and made off".
PC Chambers pursued the teenager to an alleyway, where another officer took up the chase.
The jury heard how Mitchell entered Belper station, left the platform and starting running down the tracks.
The inquest was told that the other officer, who is due to give evidence, shouted "Get off the tracks!" as the train approached, then hit him.
"I could see a large area of red shining on the platform wall," PC Chambers said.
The post-mortem examination on Mitchell's body found he sustained 22 significant injuries.
Mitchell's mother, Nicola Village, said she had not seen her son for two days before he died, following an argument that resulted in him putting a stone through the window of the family car.
"He could get angry, but damage was not something he'd usually do," she said.
Mrs Village described Mitchell as "outgoing" and "mad with skateboarding".
The inquest is expected to last three to four days.