The deputy governor's son, Muhammad, was killed in the bombing of an upscale residential compound, struck down on Monday with such force, his father Abdullah al-Blehed said, that the first time he touched his son's mangled corpse lying on the sidewalk, he did not recognize his own firstborn. 

"Those people who say they want to make jihad against the United States or Israel, what they did is pointless," said Mr. Blehed, a part owner of Al Hamra, the compound where his son died. "Jihad is not like this." 

"This time it was different: it was an attack against your own people," said Khaled M. Batarfi, the managing editor of Al Madina, a daily newspaper. "It's huge; it's organized. It's like what happened on Sept. 11 in America but on a smaller scale — these things happen to others." 

The gory scenes of charred bodies spread across their newspapers and on television are disturbing in a way other recent terrorist attacks were not. 

"If this was not the Saudis' Sept. 11, it was certainly the Saudis' Pearl Harbor," said the United States ambassador, Robert W. Jordan.

Of course there had been attacks here before. At least a half-dozen bombs planted under cars in recent years killed three expatriates and maimed several others. Americans were the main victims of both the 1996 bombing of the Khobar Towers and a 1995 attack on a Saudi National Guard center.

Saudis, however, felt secure in their own country. Now they are not so sure. 

"We're moving," said Fahd al-Blehed, 27, Muhammad's brother and his neighbor in the compound. "Those people can do anything." 

It was only in recent years that Saudis started living in compounds, long a preserve of Westerners. Muhammad, 29, was a typical local resident. After spending five years in the United States, graduating from California Polytechnic State University in San Luis Obispo with a master's degree in public administration, he came home. He followed his father into both the Riyadh government and the family real estate and transportation business. 

Life in the compounds is not unlike any California community college. Some of the tennis courts are air-conditioned. Swimming pools abound. Al Hamra boasted some 15 among its 428 villas, town houses and apartments. The five most expensive mansionettes, which rented for $10,000 per month, each had its own. 

The Saudis who lived there — and 70 percent of the residents were Saudi — tended to be married to foreign women or have spent some years abroad. The compound was out of bounds to the religious police, sniffing for moral turpitude. Women could move around unveiled. Men could wear their soccer shorts. 

When he was out walking with his wife, Fahd said, "Nobody would ask me, "Who is she? What is she doing with you?' " 

Some expect the attack on Saudis who had adopted a Western lifestyle was done on purpose. "In their belief, there is no difference, because those people are befriending the infidels," Mr. Batarfi, the editor, said. 

On the night of the attack, Muhammad was eating dinner with four friends, his family said. One was the son of another shareholder in the compound, another a lawyer. When they heard gunfire at the nearby gate, Muhammad ran for home, where his 2-month-old twin daughters had been left with a nanny. He never made it. His body was found some 10 yards from where a Chevrolet pickup truck packed with explosives was detonated. 

The explosion also killed all his dinner companions, Muhammad's relatives said. It leveled some 25 houses. A total of 100 will need to be rebuilt. It tore the roof off the gym of the British School in the compound and wrenched doors off their hinges in another compound a few hundred yards away. 

As their father describes the attack, Fahd and his younger brother Faisal, 25, tear up. With the sadness comes anger about security lapses. Fahd said the owners asked for more security for the front gate but the government provided only one armed man in a jeep — the government holding a monopoly on carrying guns. 

"That won't do much against a bunch of guys trained in Afghanistan," Fahd said, making a sudden fist. "The government has to be harder on them, especially the religious people who are even brainwashing young children in mosques." 

The need for a crackdown has been a common theme here this week. The country's newspapers, especially Al Watan, have been waging a campaign pointing out that it is not that great a leap from criticizing women as infidels for opening sports clubs to declaring open season on anyone fitting that description. 

The newspaper used to get only hate mail for such sentiments, said its editor, Jamal Khashoggi, but it has now started receiving supportive missives, demanding a crackdown on the radicals. 

Before this week, many Saudis, and especially those in government, tended to paint fanaticism as something foreign. This week, the usual statements about events "strange to our society" were absent. 

The creeping recognition that it is something homegrown has made Saudis more jittery, not least because the Web sites beloved of the radical fringe are predicting more to come. 

When a helpful Saudi took an undeniably Western reporter on a drive through Riyadh, the man's elderly father called to make sure the visitor had not provoked an assault. 

"The thinking is: `If I go to school tomorrow, will anything happen to me? If I drive by this compound will it explode? If I go someplace with a Western friend will I be attacked?' " Mr. Batarfi said.