The UN Security Council is holding an emergency meeting on terrorism in Russia -- as gunmen hold some 400 people hostage at a school in a region bordering Chechnya.
Secretary General Kofi Annan said he is "appalled" that children are among the hostages. He joined a number of world leaders in condemning the attack.
President Bush telephoned Russian President Vladimir Putin to offer his support and assistance.
The gunmen, wearing explosives, stormed the school in Beslan, North Ossetia early Wednesday, reportedly demanding Russia free Chechen rebels. They are threatening to kill 50 children for every attacker killed. At least two people have already died, including one parent who defied the captors.
It is unclear who the gunmen are, but a representative of Chechen rebel leader Aslan Maskhadov has denied involvement.
This is the third major terrorist strike in Russia in a week. A female suicide bomber killed 10 people outside a Moscow subway station Tuesday. And authorities suspect two Chechen terrorists brought down two Russian passenger jets last week, killing 90.
Information for this report is provided by AP.