Interfax news agency quoted officials on Thursday as saying that the former head of North Ossetia's neighbour Ingushetia, Ruslan Aushev, had mediated their release.
More than 300 hostages are still believed to be inside the school.
Itar-Tass agency also quoted North Ossetian spokesman Lev Dzugayev as saying that the freed hostages were in "satisfactory" condition.
Earlier, four infants and two women were also released.
Dzugayev described Thursday's release of hostages as "the first major success of negotiators".
The hostage-takers have rejected all offers to deliver food and water for hostages.
Their demands have however not been publicised as yet.
Soon after the school was seized by several masked men and women on Wednesday, about 50 children were allowed to flee the building.
Itar-Tass earlier reported Russian authorities saying 12 people had lost their lives as a result of the kidnappings on Wednesday.
More than 50 children have been
freed from the school
Authorities also claim that a hostage-taker has been killed.
The identity of the kidnappers is not known. But Russian officials have linked them to separatist groups fighting in the neighbouring region of Chechnya.
The UN has condemned the attack with France and other countries emphasising the need for a negotiated settlement in the region.
In a telephone call to Russian President Vladimir Putin, Chancellor Gerhard Schroeder offered to fly a German military mobile hospital to the region in case it should be needed, a spokesman said onThursday.
Schroeder has been roundly criticised for his recent declarations about the controversial elections in the troubled breakaway republic of Chechnya, which he said "demonstrate that Russia wants a political solution."