ABQAIQ, Saudi Arabia -- Suicide bombers carried out a bold attack on the world's largest oil processing facility Friday but were stopped from breaking in by guards who fired on their cars, exploding both vehicles and killing the attackers.
It was the first attack on an oil facility in Saudi Arabia, and suspicion quickly fell on al-Qaida. The assault raised speculation that the militants were adopting the tactics of insurgents across the border in Iraq, where the oil industry has been repeatedly targeted.
Saudi Oil Minister Ali Naimi quickly announced that the attack "did not affect operations" and that Abqaiq operations and exports "continued to operate normally." The huge Abqaiq processing facility near the Persian Gulf prepares about two-thirds of the country's oil output for export, making it a crucial link in getting Saudi crude to the market.
Crude oil futures spiked more than $2 a barrel amid fears militants would again target the vital industry. Light sweet crude for April delivery surged as high as $63.25 a barrel before settling at $62.91, an increase of $2.37 on the New York Mercantile Exchange. Brent crude futures for April delivery jumped $2.06 to $62.60 on London's ICE Futures exchange.
The attack in Abqaiq, about 25 miles inland from Saudi Arabia's eastern Gulf coast, took place at about 3 p.m. -- several hours after the weekly prayers on Friday, a day off for Saudis though the facility was in operation.
At least two militants were killed in the explosions, and Saudi-owned Al-Arabiya television reported two security guards also died. Interior Ministry spokesman Lt. Gen. Mansour Al-Turki could not confirm the deaths of the security guards but said two were critically wounded with potentially lethal injuries.
The assault began when two cars tried to drive through the gates of the outermost of three fences surrounding the processing facility, al-Turki told The Associated Press. Al-Arabiya reported that the attackers' cars bore the logo of Aramco, the state oil company that owns the facility.
Guards shot at the cars, and both vehicles exploded, al-Turki said. The explosions caused a fire that was quickly controlled, the oil minister said.
Guards then battled for two hours with two other militants outside the facility, said a Saudi journalist who arrived at the scene soon after the explosion. He said he saw workers repairing a pipeline.
For three more hours afterward, security forces searched the surrounding area, the journalist said, speaking on condition of anonymity because of his company's rules.
An AP correspondent at the site saw ambulances racing through Abqaiq's streets hours after the attack. Police had set up roadblocks leading in and out of the town. There were no immediate reports of further casualties or arrests.
The facility lies several miles from a residential area where several thousand expatriate workers -- including Americans, Europeans and Arabs -- live. Al-Turki said no foreigners were injured in the violence.
"We have no clue so far about who are the perpetrators or to what group they belong," al-Turki said. "It is still too early. We have already started the investigation."
But Saudi Arabia has been waging a successful three-year crackdown on al-Qaida's branch in the kingdom. Security forces have killed or captured most of the branch's known top leaders, most recently in gunbattles in December, after the militants launched a campaign in 2003 to overthrow the U.S.-allied royal family with a string of attacks.
There have long been fears militants would target oil facilities, but in the past they have targeted foreigners working in the industry rather than infrastructure.
"In Iraq they zeroed in on oil, and this appears to be a creeping process, since it is happening in Saudi Arabia," said Youssef Ibrahim, a Dubai-based political risk analyst with the Strategic Energy Investment Group.
Iraq's most feared terror leader, Abu Musab al-Zarqawi, heads al-Qaida's branch in that country. The two countries share a porous desert border, which militants are known to cross to join the Iraqi insurgency.
In May 2004, attackers stormed the offices of a Houston-based oil company in the western Saudi oil hub of Yanbu in fighting that killed six Westerners, a Saudi and the militants. Several weeks later, al-Qaida-linked gunmen stormed oil company compounds in Khobar, on the eastern coast, and took hostages in a siege that killed 22 people, 19 of them foreigners.
In December 2004, al-Qaida leader Osama bin Laden, a Saudi exile, for the first time called on militants to attack oil targets in the Gulf to stop the flow of oil to the West.
But no major attacks followed in the region. Some experts have believed that because al-Qaida's long-term goal is to run Saudi Arabia, it would do nothing to seriously jeopardize the oil industry on which the kingdom's wealth is based.
Friday's attack is new "in the sense that this is the boldest attempt to strike at the heart of a Saudi oil-production complex," Eurasia Group oil analyst Antoine Halff said.
Saudi Arabia holds over 260 billion barrels of proven oil reserves, a quarter of the world's total. It currently puts out about 9.5 million barrels per day, or 11 percent of global consumption.
The Abqaiq facility processes about 5-7 million barrels a day, removing hydrogen sulfide from crude oil to make it safe for shipping, before it is pumped to tankers for export.
AP correspondents Salah Nasrawi in Cairo, Donna Abu Nasr in Manama, Bahrain, and Jim Krane in Dubai contributed to this report.