BESLAN, Russia - President Vladimir Putin ordered the borders of North Ossetia closed Saturday as security forces searched the southern region for militants who escaped the Russian storming of a school where they had held hundreds of people hostage, many who fled the building under fire. A news agency reported 322 bodies were pulled from the rubble.

Another 500 or so people remained hospitalized following the bloody and chaotic gunbattle Friday. Many were said to have been killed or wounded when a roof collapsed from an explosion before the Russian assault of the building began.

"All Russia grieves with you," Putin said during a visit to the scene Saturday, carried on government television. "Even alongside the most cruel attacks of the past, this terrorist act occupies a special place because it was aimed at children."

The ITAR-Tass news agency quoted Russian Deputy Prosecutor Sergei Fridinsky as saying 322 bodies, including those of 155 children, had been recovered from the school. It was a stunning figure because Russian officials had said only a day before that there were only 350 hostages - a number that turned out to be at least three times lower than now believed.

Putin said he had ordered North Ossetia's borders closed while officials searched for suspects in the hostage-taking, carried out by militants seeking independence for the nearby republic of Chechnya.

Valery Andreyev, Russia's Federal Security Service chief in the region, said 10 Arabs were among 27 militants killed. The Arab presence among the attackers would support Putin's contention that al-Qaida terrorists were deeply involved in the Chechen conflict, where Muslim fighters have been battling Russian forces on and off for more than a decade.

The Federal Security Service chief in North Ossetia, Valery Andreyev, said more than 30 militants had seized the school. Channel One and NTV television reported that three of them had been captured.

New evidence suggested the attack had been planned long beforehand. Andreyev said Saturday that investigators were looking into whether militants had smuggled the explosives and weapons into the school and hidden them during a renovation this summer.

For some North Ossetians, grief had turned to anger.

"Fathers will bury their children, and after 40 days (the Orthodox Christian mourning period) ... they will take up weapons and seek revenge," said Alan Kargiyev, a 20-year-old university student in the regional capital Vladikavkaz.

On Friday, commandos stormed the building and battled militants as crying children, some half-naked and covered with blood, fled through explosions and gunfire. Other children lay dead on stretchers lined up outside.

Dozens of people crowded around lists of survivors posted at the Beslan hospital, searching desperately for news of loved ones who were not yet accounted for.

The majority of the dead who were found in the gym were killed by explosions before the assault began, causing part of the roof to collapse, Interfax and ITAR-Tass said, citing North Ossetian police.

Russian authorities said they stormed the building after the militants set off explosions and fired shots as emergency teams approached to collect the bodies of several men killed earlier. They said the hostage-takers had given them permission to take the corpses away.

As hostages took their chance to flee, the militants opened fire on them, and security forces - along with town residents who had brought their own weapons - opened covering fire to help the hostages escape. Commandos stormed into the building and secured it, then chased fleeing militants in the town, with shooting lasting for 10 hours.

The operation ended a 62-hour ordeal that began when masked gunmen burst into the school courtyard on Wednesday, shooting in the air and herding people into the gym.

The region's governor, Alexander Dzasokhov, said Friday that the militants had demanded that Russian troops leave Chechnya - the first solid indication that the attack was connected to the rebellion.