A father-of-two who helped rescue injured workers in the 2001 explosion at Port Talbot's Corus steelworks has died after falling into molten waste.
Two separate investigations into the accident are under way
Kevin Downey, 49, from Port Talbot, was treated at Swansea's Morriston Hospital after the accident at 0415 BST on Tuesday.
Referring to his involvement in the 2001 tragedy when three men died, Corus said he was instrumental in helping.
Colleagues and the local press had dubbed him a "hero" for his actions.
Mr Downey, who began working at the plant when he left school, was said to have been pivotal in shutting the furnace down after the explosion five years ago and making the area safe.
The 2001 blast was the worst steel industry accident in 27 years
The blast - which was the worst accident in the UK steel industry for 27 years - killed Stephen Galsworthy, who was 25, Andrew Hutin, 20, and Len Radford, 53.
Married with a daughter and a son who also worked at the plant, it appears Mr Downey fell into a piece of equipment known as a "slag runner" while working in blast furnace number four. He suffered massive burns.
Corus said the accident had "created an unbelievable amount of shock and grief".
A company spokesman said there was no explosion, venting of gas or any other obvious catastrophic failure before the accident.
Protective clothing and other systems were also said to have been working.
Flags at the plant were at half mast on Wednesday.
The Welsh Ambulance Service said it received a 999 call to go to the site at 0427 BST on Tuesday.
Two ambulances were sent to the scene and one transferred Mr Downey to hospital where he died at the burns unit late on Tuesday.
Corus confirmed that it would conduct its own investigation, which would feed into the joint police and Health and Safety Executive inquiry.
Port Talbot MP Hywel Francis said he was "deeply saddened" to hear the news.
"The whole of Port Talbot and steel communities everywhere will join with me in extending our deepest condolences to Kevin's family," he said.
"I understand that representatives of the Health and Safety Executive were present at the scene immediately following the accident and an investigation is already under way.
"I will be visiting the plant tomorrow to discuss the matter with senior management and unions."