The Russian military says crew members still inside a burning nuclear submarine docked in a northern Russia shipyard are not in any danger.

An official said Friday the undisclosed number of crew members are monitoring temperatures and carbon dioxide levels inside theYekaterinburg nuclear submarine vessel to ensure its safety.

The military says at least seven people, including firefighters,have been taken to the hospital for smoke inhalation after the fire erupted Thursday.

Russia says the blaze aboard the submarine has been brought under control and there has been no radiation leak.

The fire happened while the vessel was docked for repairs in the northern Murmansk region.

The Russian Defense Ministry said all of the submarine's weapons had been unloaded before the repairs and its reactor had already been shut down. The Delta IV class vessel is able to carry 16 intercontinental ballistic missiles.

Video footage showed large clouds of smoke rising from the area. The blaze is believed to have started on the wooden scaffolding at the shipyard.

In August 2000, Russia's Kursk nuclear submarine sank at sea, killing all 118 crew members on board.