The main commander of the guerrillas who seized a school in southern Russia last week shot one of his own men for balking at taking children hostage and later blew up two women in his band with the flip of an electronic control, Russia's chief prosecutor said Wednesday.

Offering the government's first detailed account of the hostage crisis, Prosecutor General Vladimir Ustinov depicted a harsh discipline within the group of attackers and confirmed that they were aided by a local police officer. The large bomb that blew up inside the school and triggered the deadly climax of the siege, he said, went off by accident when the hostage takers were trying to rearrange their explosives.

Ustinov disclosed these details in a briefing to President Vladimir Putin that was aired on national television. It came as officials backtracked on their claim that the hostage takers included 10 Arabs, but the Kremlin insisted that a "multinational group" of extremists was involved, and Russia's highest military officer threatened preemptive strikes against terrorist bases in other countries.

Russia's foreign minister strongly criticized the United States for suggesting this week that U.S. officials might still meet with Chechen separatist figures.

The full scale of the carnage in the southern town of Beslan remained unclear. The government put the official death toll so far at 328 children and adults. Ustinov's math suggested that the count could climb to nearly 500. He noted that more than 1,200 hostages were held and 727 received medical treatment. Virtually every survivor was taken to a hospital.

Relatives in Beslan continued to call at hospitals and morgues looking for missing loved ones. Officials in the regional center of Vladikavkaz reported that 233 of the bodies had been identified, leaving 95 undetermined. Others were likely incinerated or blown apart in the explosions that destroyed the school gym.

Officials said 32 guerrillas took part in the raid on School No. 1, all but one of whom were dead after the day-long battle that ended the impasse last Friday. Of 30 bodies found, 12 have been identified and one was torn to pieces. One attacker was taken alive, officials said.

The government, which has admitted that it initially lied about the number of hostages taken during the 52-hour standoff, rejected suspicions voiced in Beslan and Moscow that it was still covering up crucial information. Instead, it said it was simply sorting through a confusing set of facts.

"It's so terrible, we need lots and lots of time to put all of the pieces of the mosaic together," Kremlin spokesman Dmitri Peskov said in an interview.

Ustinov's briefing to Putin at the Kremlin provided the first detailed look at the prosecutors' theory of the event. Citing interviews with hostages and the lone captured guerrilla, Ustinov said the group gathered in a forest, boarded a GAZ-66 military truck and two other vehicles, then headed for Beslan. Along the way, they picked up a police officer, he said. Ustinov did not say whether the officer was a willing accomplice.

After overtaking the school, the guerrillas began unloading guns and explosives, but some appeared to have second thoughts, Ustinov said. "They asked, 'Why are we seizing a school?' " the prosecutor said.

The captured guerrilla, identified as Nur-Pashi Kulayev, told interrogators that one of the group's leaders, known as "the Colonel," "killed one of his people to intimidate the others and said he would do it to everyone if they disobeyed," Ustinov said. The same day, he added, the Colonel used a remote control to trigger the explosives belts worn by the two women in the group to enforce obedience.

A Kremlin official has said surveillance indicated that the hostage takers were arguing in the moments before the final confrontation began. But Ustinov's account suggested that the dispute did not bring about the triggering of the big explosion on Friday. Instead, he said, when "they started to rearrange the bombing system . . . for their own considerations, an explosion occurred."

The explosion set off panic, and hostages began fleeing the building.

One of the government's negotiators, Ruslan Aushev, provided new details about the chaotic moments that followed, saying the confrontation was actually precipitated by armed Beslan civilians. After the bomb in the gym went off, Russian troops held their fire, but civilian gunmen who had moved close to the school began shooting, Aushev told the newspaper Novaya Gazeta.

Russian officials called the guerrillas inside and declared that they were not attacking, but the guerrillas insisted that they were and began returning fire. Unable to control the civilians, the Russian troops had to launch their own operation, Aushev said. "Everything went down the drain when these civilians opened fire," he said.

The civilians ended up shooting some of Russia's elite special forces troops, according to Russian officials. Aslanbek Aslakhanov, a top aide to Putin, said in an interview this week that 20 members of the Alpha and Vympel special forces squads were killed, many by friendly fire. Peskov said Wednesday that the number killed was actually 10.

Peskov also said he could not confirm that 10 Arabs were among the hostage takers, as Russian officials earlier reported. "The first information was just preliminary and it needs to be checked," he said. "The only thing we can say for sure is it was a multinational group."

But Aushev's account confirmed that the hostage takers were focused on Chechnya. They gave him a letter to take to Putin, he said, in which they demanded that Russian troops be withdrawn from Chechnya and that the separatist region be turned over to the control of the Commonwealth of Independent States, a loose organization of most former Soviet republics.

The government on Wednesday put a $10 million bounty on the heads of Chechen rebel commanders Shamil Basayev and Aslan Maskhadov, whom they blamed for sponsoring the attack. Col. Gen. Yuri Baluyevsky, the armed forces chief of staff, asserted the right to launch preemptive attacks on what he termed "terrorist bases" outside Russia. "We will take steps to eliminate terrorist bases in any region of the world," he told journalists.

Russia made such statements in 2002 in threatening its neighbor Georgia, where Chechen guerrillas had taken shelter. More recently, Russian agents were convicted of assassinating a former Chechen leader in the Persian Gulf state of Qatar. Baluyevsky's statement appeared to be more threat than foreshadowing, because the Russian government is not known to have identified any such targets.

Foreign Minister Sergei Lavrov also had tough words Wednesday, faulting U.S. State Department spokesman Richard Boucher for saying Tuesday that Washington officials may still meet with Chechen opposition figures that Moscow calls terrorists. "We deem such statements to be out of place," Lavrov said in a statement.

In the North Ossetian town of Vladikavkaz, thousands of protesters took to the streets Wednesday, demanding the resignation of President Aleksandr Dzasokhov and his government for their handling of the siege. Dzasokhov said the government would leave office in two days, but he did not offer his own resignation.

Correspondent Peter Finn in Beslan contributed to this report.

Residents of North Ossetia react as Dzasokhov speaks from the balcony of the administration headquarters in the region's capital, Vladikavkaz, where thousands took to the streets to protest the government's handling of the siege.Aleksandr Dzasokhov, president of the Russian region where the school siege occurred, tells a crowd that North Ossetia's government will step down. Russia has put a $10 million bounty on Chechen rebels Shamil Basayev, above, and Aslan Maskhadov.