HEMEL HEMPSTEAD, England -- Fears that one tank could contain highly volatile fuel forced firefighters to halt their battle briefly yesterday against a blaze raging at an oil depot that spewed smoke as far away as France and caused jitters on the global oil market.
Authorities said they believe the explosion Sunday at the Buncefield depot north of London was an accident, but will examine other possible causes, including terrorism.
The 150 firefighters fighting the blaze with torrents of chemical foam withdrew at 3 p.m. after extinguishing flames in 12 of the 20 tanks that were initially ablaze, said Roy Wilsher, chief fire officer. Five hours later, his office said firefighters had resumed work after determining the fuel in the tank was not as volatile as had been feared.
The terminal stores 4.2 million gallons of fuel, and the fire has caused unease on the oil market and raised questions about safety at the nation's oil facilities.
''There is nothing to suggest that it is anything other than an accident, but we're keeping an open mind and when we get into the site we'll treat it as a . . . scene which could be a crime. We'll be doing full forensics," said Jeremy Alford, chief superintendent of Hertfordshire police. ''We'd be remiss if we didn't."
Firefighters battled the enormous fire for more than 30 hours before pulling back yesterday. Authorities shut a highway nearby and extended a closed-off zone around the depot 25 miles north of London because of the chance the tank might explode, Wilsher said.
He said flames had reignited in one tank that had been extinguished earlier.
''I don't want a human tragedy to go alongside the environmental tragedy that we've already got," he told reporters as firefighters withdrew.
Wilsher told reporters the firefighters were in ''uncharted territory."
''This is the largest fire of this kind that the U.K. and Europe have dealt with," he said.
Police said the ferocity of the blaze would make it difficult for forensic specialists to determine its exact cause, but there was no indication of foul play. Chief Constable Frank Whiteley said eyewitness accounts and closed-circuit television footage would be key to the investigation.
The explosions came four days after an Al Qaeda videotape on the Internet called for attacks on facilities carrying oil, but officials drew no link.
Deputy Prime Minister John Prescott told Parliament there would be a full investigation once the fire was extinguished.
''Does this latest incident prove that proper safety procedures were still not in place?" Caroline Spelman, Conservative Party lawmaker, asked.
Gemma Shepherdson, a spokeswoman for
She said the depot was ringed by closed-circuit TV cameras.
Heavy plumes of black smoke continued to billow yesterday from the depot, the fifth-largest in Britain.
Most of the people injured in the blast --more than 40 -- before dawn Sunday were treated for cuts and bruises from flying glass. Two men with more serious injuries remained hospitalized Sunday night, and one was released yesterday, police said.
The smoke cloud has drifted over Brittany and Normandy in northwestern France and was headed toward Spain, France's national weather service said yesterday.
Environment officials said toxins from the fire had not contaminated drinking water near Hemel Hempstead.
Most of the 2,000 people evacuated from their homes Sunday were still waiting to return.
David Smith, 65, an evacuee taking shelter in a recreation center, said he wasn't concerned about living so close to the depot.
''These places have got to go somewhere," he said. ''It's a very small island; we need these oil depots."
Jane Hogg, mayor of Dacorum Borough Council, said authorities were trying to get people back in their homes as soon as possible, but needed to be sure the buildings were structurally sound.
The oil terminal explosions raised supply concerns, but authorities said the blasts would not lead to a shortage.
Oil prices surged above $60 yesterday as forecasts of colder weather in the world's largest heating oil market, the Northeast United States, boosted expectations of a rise in demand, and the Organization of Petroleum Exporting Countries agreed to maintain its present output.
Representatives of oil companies, pipeline operators, and the airline industry met yesterday to discuss ways of keeping fuel supplies flowing. French oil firm Total S.A. said it had implemented contingency plans to reroute supplies that normally run through the plant.
''There shouldn't be any problem with supplies," said Lesley Else, a spokeswoman for Total U.K.
The Buncefield plant, part-owned by Texaco, carries jet fuel to Heathrow and Gatwick airports.