Updated

Police in armored vehicles and a helicopter closed off three Riyadh neighborhoods in a pre-dawn search Sunday for Islamic extremists and for the body of the American hostage beheaded by Al Qaeda.

Saudi Arabia's interior minister, Prince Nayef, vowed the government will eradicate terrorism in the kingdom, where the slaying of Paul M. Johnson Jr. (search) on Friday was the latest in a campaign of attacks on Weseterners.

"The state is strong in crushing the enemy and will cleanse the country," Nayef said during a meeting with local dignitaries, the Saudi Press Agency reported. Terrorists "have followed the devil's trail and found those whom they can fool."

The extensive search Sunday morning ended with no immediate word on results. Among the neighborhoods searched was al-Malaz, site of a gunbattle Friday that ended with the death of Abid al-Aziz al-Muqran (search), mastermind of Johnson's kidnapping and killing and other attacks in Saudi Arabia.

Police sealed off the neighborhoods Saturday night, searching any cars that tried to leave. Dozens of police in cars and armored vehicles moved in to search houses as other officers kept watch from a helicopter into the early morning hours.

Earlier Saturday, troops searched in the deserts around Riyadh as well as houses and apartments suspected of being used by militants, officials said.

While trying to find Johnson's body, Saudi officials are also moving to break up al-Muqran's cell. Three other militants were reported killed alongside al-Muqran in Friday night's gunbattle — including his deputy — and the Interior Ministry says 12 suspected militants wer arrested in a sweep of the capital.

The gunbattle in which al-Muqran was killed came hours after the terror group posted photographs Johnson's beheading on an Internet site. One security officer was killed and two were wounded in the gunbattle.

The three other militants killed were identified as Faisal Abdul-Rahman al-Dikheel, Turki bin Fuheid al-Muteiry and Ibrahim bin Abdullah al-Dreiham.

Adel al-Jubeir, foreign affairs adviser to Crown Prince Abdullah (search) in Washington, said al-Dikheel was believed to be the No. 2 Al Qaeda militant in Saudi Arabia "working closely and immediately under al-Muqran."

The 12 arrested suspects have not been identified, though a Saudi security official told The Associated Press early Saturday that Rakan Mohsin Mohammed al-Saikhan, listed second among Saudi Arabia's 26 most-wanted men, had been wounded and arrested.

The English-language Arab News, quoting an unidentified security source, reported Sunday that one of the 12 arrested was suspected of involvement in the 2000 bombing of the USS Cole (search) off the coast of Yemen, which killed 17 U.S. sailors.

The Interior Ministry said authorities had confiscated forged identity papers, $38,000 in Saudi and American currency, three rocket-propelled grenade launchers, hand grenades, automatic rifles and other weapons, the Saudi news agency said.

Also confiscated were three cars used by al-Muqran's cell, including one believed to have been used in the June 6 killing of Irish cameraman Simon Cumbers (search), who was filming for the British Broadcasting Corp. when he was shot. A BBC correspondent was seriously wounded.

Johnson was seized June 12, the same day that Islamic militants shot and killed Kenneth Scroggs of Laconia, N.H., in his garage in Riyadh. Earlier that week, militants in the capital also shot and killed another American, Robert Jacobs of Murphysboro, Ill.

Johnson's killing sparked a wave of outrage from around the world.

On Sunday, Iran joined the condemnations — but also blamed its longtime enemy the United States for creating the atmosphere in which Johnson was slain.

"Killing a person this way is inhumane and unacceptable," Foreign Ministry spokesman Hamid Reza Asefi told reporters. "Unfortunately, the reason behind all violence and hatred in the region is America's wrong approach in fighting terrorism."