The fire is now under control

Speaking from her home, Ms Rees said: "There is a lot of smoke bellowing but the activity seems to have calmed down.

"Obviously the whole area is well lit but because I knew the area so well I knew straight away that it was blast furnace number five, which is on the coast side of the steel works.

Ms Rees was an employee at the steelworks when the furnace was built in the 1950's.

A lot of the boys who work here are in a terrible state

Andrew Tutton, crane driver

"Making steel is a very finely tuned process but explosions like this can happen at anytime the dangers should never be underestimated," she added.

"I have seen major incidents in the works before, I have seen some horrific injuries but this seems like a much larger incident than ever before."

A number of casualties from the site have been taken to Morriston Hospital in Swansea.

Andrew Tutton is a crane driver at the steelworks and was on the site before the area was sealed off.

"I saw the black smoke and didn't really think anything of it because you see a lot of that around here," he recalled.

"I arrived for work early and got here to be told that the number five blast furnace had blown out.

I heard about three explosions. I ran out to the garden to see what it was and I could see a lot of smoke

Local Councillor Clive Owen

"They have not told us a lot about what is going on but they are treating it as a major incident.

"There are still a lot of ambulances here although a lot have already gone.

"There is also a lot of water and steam and firefighters coming in and out.

"I think the traffic has stopped on the M4 so they can get the ambulances out."

He added: "A lot of the boys who work here are in a terrible state.

"They have now closed all the entrances and nobody is allowed in. We are not sure what is going on."

Local Councillor Clive Owen said Furnace Five had been due to be relined in 2004 and contractors had been working on it as an interim measure.

"They were going to be relining it in a couple of years and I think they were patching it up," he told Sky News.

"I heard about three explosions. I ran out to the garden to see what it was and I could see a lot of smoke.

Then the fire engines and ambulances started coming in."