Smoke and flames at the site Smoke and flames at the site
Fire Crews Take On Blaze
Hundreds of firefighters are preparing to tackle a raging inferno at a fuel depot ignited by a series of large explosions.
Hertfordshire Chief Fire Officer Roy Wilsher said fire crews were ready to mount "a sustained attack" on the fire using supplies of concentrated foam shipped in from round the country.
The blast injured 43 people and has been described as the "largest incident of its kind in peacetime Europe".
The first blast near Hemel Hempstead was so powerful it rocked houses up to 40 miles away and was heard in Holland.
More than 60 billion gallons of fuel erupted in a ball of flames hundreds of feet in the sky, creating an acrid cloud of smoke which is stretching for miles and moving south-eastwards.
A picture sent to Sky News by a viewer A picture sent to Sky News by a viewer
Most of the casualties had only minor injuries from flying glass but one person is seriously hurt and another is under observation in hospital.
People near the smoke are being warned to stay inside and close all windows and doors. Authorities in the region have been handing out breathing masks.
Dr Jane Haplin, of Hertfordshire Health Authority, said experts believed the smoke was largely made up of carbon dioxide and carbon monoxide, which was reassuring.
She said: "If there was going to be a large-scale reaction I would expect that we'd have started to see the signs of it by now and that doesn't seem to be happening."
Breathing masks are needed Breathing masks are needed
The first blast happened at the Buncefield depot, around 25 miles north of London, just after 6am. Two smaller blasts happened about 20 minutes later.
Police have said that although the situation is now under control, they expect more blasts at the site, which stores 16 million litres of petrol, kerosene and diesel.
Police have urged people not to panic-buy petrol. They say contingency plans are in place and there is "nothing to suggest" there will be a supply problem.
All nine refineries in the UK are fully operational, with no problems related to the manufacture of petroleum or their distribution other than at Buncefield, an industry spokesman said.
Map of the area Map of the area
Houses near the depot have been evacuated and part of the M1 has been closed in both directions.
Police say schools, libraries and day centres will be closed tomorrow and warned motorists to steer clear of the area.
The cause of the explosions is not yet known but no third party - a plane or a terrorist - was involved.
Thousands of viewers have contacted Sky News with reports it shook houses many miles away.
Witnesses said buildings have been brought down and the roofs of houses were lifted by the force.
One witness said he was near the site when the blasts happened and he saw a building "open up like a doll's house".
Sky News Correspondent Geoff Meade heard the blast at his home and broke the news to the nation.
He immediately called Sky Centre in west London, which was also shook by the explosions, and described "burning tongues" of flames in the sky.
:: An emergency hotline has been set up to help anyone concerned about friends or relatives. The number is 0800 096 0095.
Location of Hemel Hempstead within the UK
A shot of the fire taken near the depot

A series of large explosions have occurred close to Hemel Hempstead  Hertfordshire, UK. The source of the explosions has been confirmed as the Hertfordshire Oil Storage Terminal (HOSL), Hemel Hempstead, known locally as the Buncefield complex. Up to  150 fire fighters are reported to be at the scene with 10 fire appliances and 1 specialist foamer.

The first 'blast' was heard near Hemel Hempstead on Sunday 11 Dec at 6 am. Further smaller explosions followed at 6:24am , 6:26am, 6:30am. BBC News 24 reported an additional, fourth large explosion.  Hertfordshire Police Constabulary are currently treating the explosion as an accident.  

Reports say the explosion, which registered 2.4 on the Richter scale, was heard as far away as Oxford, and Whitehall, Central London which is 60km (38 miles) away. Eyewitness statements report that the explosion was heard from at least 160km (100 miles) away and as far away as France and The Netherlands. Pilots reported noticing the blast from the North Sea and the West Country area of the UK.  The M1 motorway which runs close by has been closed in both directions near the blast which is causing travel chaos as other roads become congested.

Malcom Stewart, a BBC News24 eyewitness who is a tanker driver for the site has reported that the site supplies several oil companies and is a joint operation between Total UK and Texaco, it is also used by BP, Shell and the British Pipeline association. The complex is not a refinery but a storage facility for refined petroleum awaiting distribution to airports and filling stations. The eyewitness reports that the depot has approximately 20 tanks which can hold about 3 million gallons (11 million litres or 70,000 barrels) each.  Another News24 eyewitness has just reported that he has seen at least 5 of these tanks on fire.

Satellite image of Hemel Hempstead fuel explosion showing black smoke from the explosion near London

The depot operates on a 24 hour basis and is split into 2 parts - aviation fuel and domestic fuel.  A number of eyewitnesses have reported on UK news that the aviation fuel side appears to be the part of the site that has been affected.

Local authorities were not immediately available for comment but there have been reports of casualties.

Some reports on live television state that, "Several other neighbours said they did see a plane go into the depot."  BBC News 24 were also discussing the idea a possible plane crash as the cause of the explosions.  Hertfordshire police have now gone on the record to say that there is no plane involved (BBC News24).

The police have issued a contact number 0800 096 0095 and asked that people do not call the emergency services in Hertfordshire directly unless it is an emergency. 
Buncefield Fire, taken from Dunsmore, Bucks - about 20miles away.

In addition to being an oil storage depot, it is a major hub on the UK oil pipeline network with pipelines to Killingholme Lindsey Oil Refinery (LOR), Humberside (10 inch), Merseyside (10 and 12 inch), Coryton on the Thames Estuary (14 inch) and Heathrow (6 and 8 inch) and Gatwick airports radiating from it.

The disaster is believed to be the worst explosion at a petrochemical plant in the UK since the Flixborough disaster of 1974.
Hertfordshire's Chief Fire Officer Roy Wilsher said: "This is possibly the largest incident of its kind in peacetime Europe." 

A firefighting press officer said that they are stock piling foam from neighboring regions for a prolonged attach which they hope will stop the spread of the fire, however, the inferno itself will have to burn out which could take between 24 hours and a few days.

Despite the authorities saying that there is no need to panic buy petrol, filling stations have had above average queues since this morning and some small garages have ran out.

Deputy Prime Minister John Prescott has visited the scene.

Smoke Viewed from St Albans