The Buncefield fire was a major conflagration

Conflagration

A conflagration or a blaze is an uncontrolled burning that threatens human life, health, or property. A conflagration can be accidentally begun, naturally caused , or intentionally created . Arson can be accomplished for the purpose of sabotage or diversion, and also can be the consequence of...

 caused by a series of explosion

Explosion

An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

s on 11 December 2005 at the Hertfordshire Oil Storage Terminal

Hertfordshire Oil Storage Terminal

Hertfordshire Oil Storage Terminal is operated by Hertfordshire Oil Storage Ltd and commonly known as the Buncefield oil depot. It is an oil depot located on the edge of Hemel Hempstead to the north of London in the United Kingdom...

, an oil storage facility located near the M1 motorway

M1 motorway

The M1 is a north–south motorway in England primarily connecting London to Leeds, where it joins the A1 near Aberford. While the M1 is considered to be the first inter-urban motorway to be completed in the United Kingdom, the first road to be built to motorway standard in the country was the...

 by Hemel Hempstead

Hemel Hempstead

Hemel Hempstead is a town in Hertfordshire in the East of England, to the north west of London and part of the Greater London Urban Area. The population at the 2001 Census was 81,143 ....

 in Hertfordshire

Hertfordshire

Hertfordshire is a ceremonial and non-metropolitan county in the East region of England. The county town is Hertford.The county is one of the Home Counties and lies inland, bordered by Greater London , Buckinghamshire , Bedfordshire , Cambridgeshire and...

, England. The terminal was the fifth largest oil-products storage depot in the United Kingdom, with a capacity of about 60000000 gallons (272,765,400 l) of fuel. The terminal is owned by TOTAL UK Limited

Total S.A.

Total S.A. is a French multinational oil company and one of the six "Supermajor" oil companies in the world.Its businesses cover the entire oil and gas chain, from crude oil and natural gas exploration and production to power generation, transportation, refining, petroleum product marketing, and...

 (60%) and Texaco

Texaco

Texaco is the name of an American oil retail brand. Its flagship product is its fuel "Texaco with Techron". It also owns the Havoline motor oil brand....

 (40%).

The first and largest explosion occurred at 06:01 UTC

Coordinated Universal Time

Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...

 near tank 912, which led to further explosions which eventually overwhelmed 20 large storage tanks.
The emergency services announced a major emergency at 06:08 and a fire fighting effort began.