ABQAIQ, Saudi Arabia — A burst of gunfire and explosions thwarted an attempt to strike at the heart of the Saudi oil industry.

Suicide bombers in two explosives-laden cars tried to storm into Abqaiq — the largest oil processing facility in the world — a few hours after weekly noon prayers on Friday, possibly hoping to catch guards by surprise on what is normally the quietest day of the week.

But guards opened fire, detonating the vehicles before they reached the gates, Saudi officials said.

Even though it failed, the attack raised fears that militants who have been on the run in the kingdom were now resurgent and targeting the oil industry.

The al-Qaida terror group purportedly claimed responsibility, saying two of its militants carried out the suicide attack. The claim was posted on a Web site frequently used by terror groups but there was no way to check its authenticity.

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. 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.