A railway worker among the first to arrive at a fire in a tunnel underneath the River Thames, has described finding his badly injured colleague.
Kevin Rix told an inquest in Kent that train driver Douglas Lynch, 50, "looked like some plastic bags on the walkway".
"I just couldn't believe that it was him," he said. "I knew it was really serious."
Mr Lynch died four days after the fire in 2005. Shunter Darren Brown, 40, from Manchester, died at the scene.
The men were involved in the construction of the second phase of the Channel Tunnel high-speed rail link, connecting Cheriton, near Folkestone, to St Pancras station in central London.
The inquest in Gravesend heard that Mr Lynch and Mr Brown were transporting a Newag locomotive carrying materials through one of two 2.5km tunnels linking Thurrock in Essex and Swanscombe in Kent.
The fire, on 16 August, followed an explosion, the force of which was so great that pieces of metal were blasted through the walls of the vehicle.
Mr Rix and his colleague Michael Moore were the first to reach the blazing locomotive.
Mr Rix said Mr Lynch, known as Dougie, was conscious but in a lot of pain.
He said that after radioing for help he told Mr Moore to stay with Mr Lynch while he went looking for Mr Brown.
"When I looked into the locomotive I just couldn't imagine that someone was going to be alive in there," he said.
He said he could not walk down the tunnel any further because of the acrid smoke so instead he tried to fight the fire with extinguishers he found nearby.
Mr Brown's body was not found until some hours later, lying about 540 yds (500m) away from the 260ft (80m) locomotive, the inquest heard.
A post-mortem examination on the father-of-two found he had died of multiple injuries including flash burns and a severe head injury.
Mr Lynch, also a father-of-two, later died in hospital from severe burns.
Counsel to the inquest Christopher Sutton-Mattocks told jurors that Mr Lynch, from Folkestone, and Mr Brown, from Sale, were employed by sub-contractors for ACT Joint Venture.
The men took over the locomotive from two colleagues after lunch and were warned it seemed to have a mechanical problem as it had broken down twice that morning.
He said the explosion happened between 1829 BST and 1847 BST.
An examination of the locomotive concluded there was an explosion in its gear box.
Mr Sutton-Mattocks said that what caused the explosion would be for the jurors to consider.
The speed of the vehicle, the suitability of the locomotive for the job and whether it was powerful enough, along with its maintenance record and the health and safety precautions would also be matters for the jury, he said.
The inquest continues.