Al Qaeda militants kill American hostage
Terrorist group leader, 3 others die in Riyadh gunbattle
Paul Johnson Jr. was beheaded by his captors in Saudi Arabia.
Secretary of State Powell condemns the killing as barbaric.
CNN analyst: Beheading could backfire on terrorists.
(CNN) -- Saudi security forces killed a top al Qaeda leader in the kingdom shortly after the decapitated body of American hostage Paul Johnson Jr. was left in a remote area of Riyadh, security sources said.
Abdel Aziz al-Muqrin, the self-proclaimed military leader of al Qaeda in Saudi Arabia, was killed while disposing of Johnson's body, the sources told CNN.
But a statement attributed to al Qaeda denied al-Muqrin's death, saying "Saudi tyrants" trying to discourage the mujahideen were spreading "false news."
There was no way to immediately confirm the denial.
Three other terror suspects also were killed, including the second most wanted man in Saudi Arabia, Rakan Alsaykhan, who had close ties with the al Qaeda mastermind of the October 2000 bombing of the USS Cole.
The other two suspects -- brothers named Bandar and Faisal Aldakheel -- were also on the Saudi "most wanted" list, the sources said
All four were slain after a police chase and gunbattle in the Saudi capital, the sources said. Five Saudi security forces were killed.
Johnson, a 49-year-old Lockheed Martin Corp. employee, was kidnapped in Riyadh last Saturday.
His body was found Friday in northern Riyadh soon after an Islamist Web site posted photographs of his decapitated body.
U.S. officials said the remains were "definitely" Johnson's.
One photograph showed a severed head sitting on the back of a headless body.
Al-Muqrin had threatened Tuesday to kill Johnson in 72 hours unless the Saudi government released al Qaeda prisoners and Westerners left the Arabian Peninsula.
"As we promised, we the mujahedeen from the Falluja Squadron slaughtered the American hostage Paul Johnson after the deadline we gave to the Saudi tyrants," said a statement on the Web site that has been translated from the Arabic.
"So he got his fair share from this life and for him to taste a bit of what the Muslims have been suffering from Apache helicopter attacks. They were tortured by its missiles."
Johnson worked on Apache attack helicopters in Saudi Arabia and had lived there for more than a decade.
Johnson's family in the United States, including his son, daughter, brother and sister, has asked for privacy. The family issued a statement thanking everyone "for the outpouring of support they have received."
The family also praised the United States and Saudi Arabia for doing "everything they possibly could to rescue Paul under very difficult circumstances."
Lockheed Martin spokesman Tom Jurkowsky said the company is "dealing with the family."
"All we can say is we're very distressed, very disheartened," Jurkowsky said.
President Bush offered his sympathies to Johnson's family.
Speaking in Seattle, Bush also said, "The murder of Paul shows the evil nature of the enemy we face. ... We must pursue these people and bring them to justice before they hurt other Americans."
'We did everything we could to find him'
Al-Arabiya first reported al-Muqrin's death. Video from the scene showed police moving people away from a crowded residential area of the capital.
Shortly before the news broke, Adel Al-Jubeir, the foreign affairs adviser to Saudi Crown Prince Abdullah, told reporters in Washington that Saudi security forces discovered terrorist suspects fleeing in cars, gave chase and then battled them in central Riyadh.
"A number of terrorists have been killed," he said. "We believe they are part of the al Qaeda network in the kingdom. We don't know how related they are to the murder of Mr. Johnson."
Shortly after his kidnapping, Paul Johnson Jr. was shown in this video posted on a Web site linked to al Qaeda.
More than 15,000 Saudi security forces, working with U.S. forces, combed areas believed to be al Qaeda hubs in recent days, searching about 2,000 locations for Johnson and his captors, Al-Jubeir said.
"We did everything we could to find him. And we are deeply sorry that it was not enough," he said.
As news of Johnson's killing spread, U.S. officials condemned the terrorists.
Frank Lautenberg -- a Democratic senator from Johnson's home state of New Jersey -- issued a scathing indictment of Saudi Arabia's efforts to combat terrorism.
"The Saudi Arabian government has shown too much patience for these terrorist cells and the ideologies of hate they preach. The United States will no longer tolerate Saudi neglect of the extremists and terrorists who live and thrive in the kingdom," Lautenberg said.
"All further relations with Saudi Arabia must be entirely contingent on the kingdom's progress cracking down, reigning in and snuffing out its terrorist problem. Deeds -- not words -- must be the benchmark of Saudi progress in solving the terrorist problem that threatens its society as much as it threatens our own."
'A tremendous sadness'
Carol Kalin, the media attaché to the U.S. Embassy in Riyadh, said the embassy and the American community in Saudi Arabia felt "a tremendous sadness at Paul's death."
Kalin said the embassy has been in close contact with Johnson's widow, Noom, who earlier in the day tearfully pleaded for his release.
"What can I do for him?" said Noom, a native of Thailand. "I want to see him come back to see me. He don't do anything wrong, he nice with the people. I never see him have problem in the 10 year here. Never."
Kalin said the embassy is "strongly urging Americans to depart" Saudi Arabia and urging "those Americans who do choose to remain to exercise the utmost caution."
"It's tough times out here," she said.
Al-Muqrin had claimed responsibility for Johnson's kidnapping and the death of another American, Kenneth Scroggs, on Saturday on behalf of a group called the Falluja Squadron, which claims to have ties to al Qaeda.
A senior U.S. State Department official in Washington told CNN the United States will now act to "batten down the hatch and [not] give them an easy target."
"We want Americans to leave. We want the people that are there to take appropriate precautions," the official said.
The official added that Johnson lived away from the heavily fortified expatriate compounds and "was a sitting duck."
The al Qaeda Web statement also said the killing was "a lesson for them to learn for whoever comes to our country, this will be their punishment."
Muslim friends of Johnson -- including some clerics -- had also pleaded for his release. But the militants were not swayed.
The Web statement addressed those pleas.
"A lot of voices were very loud, expressing their anger for taking a Christian military person as a hostage and killing him while they kept their mouth shut from saying anything supporting those poor Muslims who are in prisons and being tortured by the hands of the cross-believers," the Web site statement said, an apparent reference to the abuse of Iraqis held at Abu Ghraib prison.