Workers at an oil refinery in Lincolnshire, had a "lucky escape" after a blast ripped through the plant creating sparking a huge blaze, fire fighters said last night.
Police said the blast, at the Killingholme refinery near Grimsby in Humberside, was "a major incident" and eyewitnesses described an intense fire billowing vast plumes of black smoke.
Two people suffered minor injuries in the explosion at the plant at South Killingholme, near Immingham, in north Lincolnshire, which sent tremors through the surrounding area and flames leaping into the sky.
More than 100 firefighters tackled the blaze and seven ambulances and an air ambulance were called to the 480-acre site.
All 199 workers at the plant at the time were accounted for, although the fire service said things could have been worse had it happened on a full working day.
"There was blast damage to surrounding offices and if workers had been in there, as they would have been had it not have been a bank holiday, they would have been at risk from flying debris," said Mr Richard Hannigan, divisional officer for Humberside Fire Brigade.
"Those who were on site had a lucky escape. There could have been many more injuries."
One of the injured workers, who was understood to have been hit by flying debris, was taken to hospital in Grimsby. Another was treated for shock.
There was damage to around 50 acres of the site after the blast at the saturated gas plant at the Humber refinery.
Conoco said no cause had yet been established but an internal inquiry had begun in conjunction with the Health and Safety Executive.
Construction of the refinery, near the ports of Immingham and Grimsby, began in 1966 and was completed in 1969 at a cost of £50 million. Since then, Conoco has invested millions to enhance efficiency, safety and environmental protection.
Refinery capacity has more than trebled since the plant was built and currently stands at 85 million barrels (11.5 million tons) a year.
A spokesman for Conoco, a major US oil company, said all but two of the units at the plant had been shut down and would remain closed until further notice.