RIYADH, Saudi Arabia -- Police cars and armored vehicles flooded the al-Malaz neighborhood in the Saudi capital Sunday as security forces surrounded a house where suspected militants were believed to have taken refuge after a shootout with police.
The massive operation was underway in the same district that was the focus of a huge security sweep against militants sought in the beheading of American hostage Paul M. Johnson Jr., whose body has still not been found.
Johnson's kidnappers had help from sympathizers within the Saudi security forces, according to an account of the operation posted by the al-Qaida cell on an Islamic extremist Web site Sunday. The sympathizers gave police uniforms to the militants, who then snatched the American engineer at a fake checkpoint in the city, the posting said.
The account highlighted fears that some diplomats and Westerners in the kingdom have expressed, that militants have infiltrated Saudi security forces, a possibility Saudi officials have denied.
Saudi King Fahd vowed that militants in the kingdom would be stopped.
"The perpetrators of these attacks aimed at shaking stability and crippling security -- and it is a far-fetched aim, God willing," he said in a speech Sunday to the advisory Shura Council. "We will not allow this destructive bunch, led by deviant thought, to harm the security of this nation or affect its stability."
Police barricaded off the al-Malaz district in Riyadh, where security forces were surrounding the house. Witnesses told The Associated Press that they saw shooting between suspects and police before some men fled on foot, seeking refuge in the building.
It was the same area where Abdulaziz al-Moqrin, believed to be the leader of al-Qaida in Saudi Arabia, and three other militants were killed in a shootout with Saudi security forces on Friday, hours after their cell killed Johnson and posted photos of his body and severed head on a Web site.
The foreign affairs adviser of Crown Prince Abdullah in Washington, Adel al-Jubeir, said Saudi officials were still looking for Johnson's body. "We are still combing through neighborhoods. And we hope that eventually we'll find the body and restore it to his family," he told CNN's "Late Edition."
According to the account of Johnson's kidnapping, militants wearing police uniforms and using police cars set up a fake checkpoint June 12 on al-Khadma Road, leading to the airport, near Imam Mohammed bin Saud University.
"A number of the cooperators who are sincere to their religion in the security apparatus donated those clothes and the police cars. We ask God to reward them and that they use their energy to serve Islam and the mujahedeen," the article read.
When Johnson's car approach-ed the checkpoint, the militants stopped his car, anesthetized him and carried him to another vehicle, the article said. Earlier Saudi newspaper reports had also said Johnson was drugged during the kidnapping.
The article said they then blew up Johnson's car.
Security officials said last week that Johnson's car was found near Imam University. Saudi press reports said the car was booby-trapped and later caught fire.
In a separate article on the Web site, al-Moqrin justified the killing of Johnson, pointing to his work on Apache attack helicopters for Lockheed Martin.
Johnson "works for military aviation and he belongs to the American army, which kills, tortures and harms Muslims everywhere, which supports enemies [of Islam] in Palestine, Philippines, Kashmir," al-Moqrin wrote.
Al-Moqrin replied to critics urging the release of Johnson, saying: "Do those people want to see this infidel carry on the killing of the children and the raping of the women in Baghdad and Kabul?"
The articles appeared in Sawt al-Jihad, or Voice of the Holy War, a semimonthly Internet periodical posted by al-Qaida in the Arabian Peninsula.
The same day Johnson was seized, Islamic militants shot and killed another American, Kenneth Scroggs of Laconia, N.H., in his garage in Riyadh. Earlier that week, militants in the capital also shot and killed Irish cameraman Simon Cumbers, who was filming for the British Broadcasting Corp. when he was shot, and another American, Robert Jacobs of Murphysboro, Ill.
After the kidnapping, Johnson's captors said they would kill him on Friday unless Saudi Arabia released jailed al-Qaida militants -- a demand the Saudi government refused.
Sunday's al-Qaida article said the militants decided to behead Johnson when al-Jubeir declared that Saudi Arabia would not negotiate with the kidnappers.
"The stupid Saudi government took the initiative and announced by the Americanized tongue Adel Al-Jubeir that it will not submit to the conditions of the mujahedeen," the statement read.
The group said it beheaded Johnson, 49, when its deadline expired Friday.
Asked about the al-Qaida statement, al-Jubeir said Sunday on CNN: "We have never negotiated with terrorists. We don't intend to do so. I believe what the al-Qaida people were trying to do is trying to justify a murder that is unjustifiable under any faith or under any principle of humanity."
Al-Moqrin was killed along with three other militants in a Riyadh gunbattle Friday night, hours after photos of Johnson's body and severed head were posted on a Web site.
The others killed were identified as Faisal Abdul-Rahman al-Dikheel, Turki bin Fuheid al-Muteiry and Ibrahim bin Abdullah al-Dreiham. Al-Jubeir said al-Dikheel was believed to be the No. 2 al-Qaida militant in Saudi Arabia "working closely and immediately under al-Moqrin."
One security officer was killed and two were wounded in the gunbattle, the official Saudi news agency reported.
The Interior Ministry said 12 suspected militants also were arrested in a sweep of the capital.