Updated

An Arab magazine claimed Tuesday that a purported member of Usama bin Laden's Al Qaeda (search) terrorist group had sent them an e-mail claiming responsibility for Saturday's homicide bombing in Riyadh (search) that killed 17 people and left more than 100 wounded.

Also on Tuesday, Reuters news service reported that Saudi security forces had detained a group of suspects believed to be involved in Saturday's deadly bombing.

"We struck Muhaya (search) compound," the London-based weekly Al-Majalla quoted an e-mail from a purported Al Qaeda operative identified as Abu Mohammed al-Ablaj as saying, referring to the residential compound attacked Saturday.

Saudi and U.S. officials investigating Saturday's attack had already suspected and blamed Al Qaeda for the bombing, but this is the first indication of a claim of responsibility. The terror network, led by Saudi-born Usama bin Laden, opposes the United States and the Saudi ruling family.

The magazine, which appears on Fridays, said the e-mail was first seen late Monday and released a statement about it to The Associated Press on Tuesday.

Al-Majalla magazine began receiving e-mails from al-Ablaj earlier this year. A U.S. counterterrorism official has said al-Ablaj was believed to be a leading Al Qaeda figure also known as Abu Bakr.

The magazine also reported previously that it received an e-mail warning from al-Ablaj of attacks in Saudi Arabia a day before the May 12 homicide bombings in Saudi Arabia. Those bombings resembled Saturday's attack, hitting a residential compound housing foreigners and killing and wounding Arabs as well as Westerners.

The latest al-Ablaj e-mail addressed criticism that Saturday's strike hurt Arabs and Muslims, not Americans, saying Al Qaeda also believed "working with Americans and mixing with them" was forbidden.

Saturday night's car bombing was portrayed by Saudis as proof of Al Qaeda's willingness to shed Arab and Muslim blood as well in its zeal to bring down the U.S.-linked Saudi monarchy. Al Qaeda has long opposed the Saudi royal family, accusing it of being insufficiently Islamic and too close to the West, particularly the United States.

At least 13 of those killed in Saturday compound attack were Arabs, with four still unidentified, Saudi official news agency quoted a Saudi Interior Ministry official as saying. Five were children. In addition, 122 people were injured, among them some Americans but most of them Arab.

The al-Ablaj e-mail said an Al Qaeda member was killed in a "battle in Riyadh," but it was unclear if the reference was to Saturday's attack. Saudi authorities have engaged in several deadly clashes with Al Qaeda suspects in Riyadh and elsewhere in recent weeks.

There has been no official word from Saudi authorities on how many attackers were killed Saturday. The pan-Arab newspaper Al-Hayat reported Tuesday that the investigation showed two people were in the car packed with explosives.

Following a Cabinet meeting Monday, King Fahd vowed to capture the "terrorists" behind the attack and their supporters. He said the kingdom "will strike with an iron fist all those who try to meddle with the security of the country and the stability and safety of its citizens and residents," the Saudi Press Agency reported.

The U.S. Embassy slightly eased restrictions on its staff and families Monday after the bombing in Riyadh (search).

Security was tight elsewhere in Saudi Arabia, though, amid fears of more attacks like Saturday's homicide car blast that also wounded scores of people. Officials have said the bombing bore similarities to previous Al Qaeda-suspected operations.

U.S. Deputy Secretary of State Richard Armitage, during a tour of the Middle East over the past few days and in comments Monday on Al-Arabiya television, said the attack appeared aimed at bringing down Saudi Arabia's ruling royal family.

After a review of the threat level, U.S. Embassy staff and their families were told they could travel outside Riyadh's heavily guarded diplomatic quarter, to which they had been restricted since the attack, an embassy spokeswoman said.

The embassy, which had closed Saturday before the bombing because of warnings of an imminent terror attack, is shut indefinitely. The State Department has made no decision to evacuate diplomats or dependents.

Saudi authorities, who have clashed recently with suspected Al Qaeda militants, said earlier this month they were increasing security in the holy city of Mecca. Security officials were particularly concerned about the last 10 days of the fasting month of Ramadan, when some 2 million Muslims are expected to perform the "omra," or minor pilgrimage, to Mecca. Ramadan ends around Nov. 24.

After a Nov. 3 shootout in Mecca that left two suspects dead, Saudi authorities confiscated a large cache of weapons in the city, birthplace of the Muslim Prophet Muhammad, leading to fears a strike was planned in Mecca.

Saturday's car bombing was portrayed by Saudis as proof of the Al Qaeda network's willingness to shed Arab and Muslim blood as well in its zeal to bring down the U.S.-linked Saudi monarchy.

The Associated Press contributed to this report.