Submarine on fire.

On 7th April K-266 Orel (Eagle) caught fire during some repairs in Zvezdochka Shipyard in Severodvinsk. Insulation material in the ninth section of the sub has caught fire during welding works done by shipyard's workers.
Nuclear reactor was shut down, and the fuel was unloaded before the repairs started so there was no risk for radioactive contamination.

The sub was burning for 3 hours. There was no information about casualties on board of the sub.

K-266 Orel is an Oscar-class submarine the same type as Kursk which sunk in 2000 during exercise on Barents Sea. Both Kursk and Orel are type 949A which is designated Oscar II in NATO codenames.

Update.
Video showing the sub burning.

Sources: FlashNord, RT News, RIA