Russia called for an emergency meeting of the U.N. Security Council Wednesday on the hostage-taking at a school in a region bordering Chechnya (search).

The U.S. State Department, U.N. Secretary-General Kofi Annan (search) and the head of the U.N. children's agency demanded the immediate release of the captives.

The Security Council, which normally does not meet on the first day of the month when a new president takes over, scheduled consultations at 5 p.m. EDT on the school seizure and several other issues.

Attackers wrapped in bomb belts seized a school in the Russian region of North Ossetia (search) on Wednesday and were holding hundreds of hostages, reportedly including 200 children, They have threatened to kill them or blow up the building if it is attacked by Russian troops. Several people were reported killed.

The assault came a day after a bomber killed at least nine people at a Moscow subway station.