Russia said it had won the battle with a raging blaze aboard a nuclear submarine on Friday by submerging the stricken vessel at a navy shipyard after hours of dousing the flames with water from helicopters and tug boats.
There was no radiation leak, authorities said.
Television pictures showed a giant plume of smoke above the yard in the Murmansk region of northern Russia as over 100 firemen struggled to douse flames which witnesses said rose 10 metres (30 feet) above the Yekaterinburg submarine.
"The fire has been localized," Emergencies Minister Sergei Shoigu told officials who were leading the firefighting effort from an emergencies control room in Moscow more than nine hours after the blaze began on Thursday.
Mr. Shoigu's comments indicate the fire was still burning but that efforts to partially sink the submarine at the dock had succeeded in reducing the intensity of the flames.
Russia said the nuclear reactor had been shut down and all weapons had been removed from the 167-metre (550 feet) Yekaterinburg, which launched an intercontinental ballistic missile from the Barents Sea at a firing range thousands of miles away in Kamchatka as recently as July.
"Radiation levels are normal," a spokeswoman for the Emergencies Ministry said. "No one was injured."
After hours of trying to put out the flames, officials decided to partially submerge the hull of the 18,200-tonne submarine at the Roslyakovo dock, one of the main dockyards of Russia's northern fleet 1,500 km (900 miles) north of Moscow.
Local media reports were vague, but the blaze was believed to have started when wooden scaffolding caught fire during welding repairs to the submarine, which had been hoisted into a dry dock.
The submarine can carry 16 ballistic missiles, each with four warheads. Its nuclear reactor was not damaged in the fire and Russian navy submarine reactors are built to withstand enormous shocks and high temperatures.
"The reactor has been shut down and does not pose any danger," Interfax news agency quoted a source at navy headquarters as saying.
Russia's worst post-Soviet submarine disaster occurred in August, 2000, when the Kursk nuclear submarine sank in the Barents Sea killing all 118 crewmen aboard.
President Dmitry Medvedev and Prime Minister Vladimir Putin have been informed about the incident, said Deputy Prime Minister Dmitry Rogozin, who oversees the military.