Two people have been hurt in an explosion at Tata’s main Welsh steelworks plant in the early hours.
Residents living near the Port Talbot plant spoke of hearing a “massive” blast shortly after 03:30 BST.
Images posted on social media show flames at the site and plumes of smoke.
Tata Steel said the explosion came from a train used to carry molten metal, but the fires at the plant were now out and all employees had been accounted for.
The firm posted on Twitter: “We can confirm two of our employees were slightly injured when there was a spillage of liquid iron while it was travelling to the steel plant.
“All fires have now been extinguished. A full investigation has begun.”
The steel firm said the site had reopened by 07:00.
Helicopters were circling overhead and South Wales Police said it received “numerous calls” shortly after 03:30 “reporting an explosion”.
Lance Davies, who lives at the highest point in the town, said it was a “miracle” no-one was killed.
“I was woken up this morning by what sounded like thunder, I went to the window and could see the results of the first explosion, then I called my partner and saw the other two,” he said.
“It was like a big orange bubble of flame in the sky, a big mushroom cloud. The whole place was lit up.
“My partner was feeling sick, she thought that was the end of us. We are a mile away but it felt so close.”
Sharon Freeguard, a Neath Port Talbot councillor, said: “I thought I heard about two to three explosions. It was extremely frightening and very, very scary.
“The house just shook, so it was quite alarming. Once it was over, I did wonder what it was and just did think about the works.
“We’re just all relieved that there are no fatalities.”
‘The house shook’
Local resident Craig Williams told the BBC he heard “an almighty bang”.
“It’s very unusual to hear something of that magnitude,” he said.
“It was just a huge bang. The house shook a little. It’s not something we are accustomed to.”
Mr Williams said Port Talbot “revolves around this plant” and it helps to “bring the community together”.
The steelworks is the largest in the UK and employs more than 4,000 people.
South Wales Police said: “The explosion caused some small fires which are all under control and damage to some buildings on the site.”
The force added that there was no need for concern about hazardous effects from the smoke.
Mid and West Wales Fire and Rescue Service said firefighters remained at the scene, but it was starting to reduce the number of crews on site.
The explosion was heard as far away as Bridgend, 14 miles (22km) from the blast, and the National Police Air Service’s St Athan wing confirmed a helicopter had been scrambled to the scene.
Aberavon MP Stephen Kinnock said the incident “raises real concerns about safety at the works”.
“It could have been a lot worse. Grateful as always to the emergency services for their rapid and effective response,” he wrote on Twitter.
“Tata Steel Europe must conduct a full review, to improve safety.”
Tata had recently invested £50m in the plant to refit a blast furnace. It has pledged to invest £1bn over 10 years if market conditions allow.
At the scene – BBC reporter Will Fyfe
“I’m stood just very close to one of the main entrances to the plant and actually everything so far seems to be business as normal this morning.
“There’s the normal traffic – shift workers coming in and out.
“The activity this morning really is in stark contrast some of the very dramatic photographs and footage – and some of those eyewitness accounts that talk about an explosion that was so loud it had blown bedroom doors open of some of the houses of people living nearby.”
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