Huge explosions and flames ripped through a Russian military arsenal for hours, killing two firefighters and sending personnel fleeing to a bomb shelter to wait out the worst of the firestorm, officials said.
The dozens who took refuge in the shelter Friday were at first feared trapped in the conflagration, but later emerged safe _ dispelling initial worries of a high death toll. But a subsequent report said 11 others were unaccounted for.
Russian TV broadcast footage of orange flames and thick smoke clouds rising from the naval munitions facility in Ulyanovsk, a city 720 kilometers (430 miles) east of Moscow.
Frequent explosions set off firebursts high in the night sky. The blasts broke apartment windows near the facility and set off car alarms miles (kilometers) away, residents told Russian media.
"There was a loud bang, then there was silence and then explosions, explosions, explosions _ like fireworks on New Year's," resident Igor Komandin told Channel One television.
The blasts and blaze erupted while ammunition was being destroyed at the facility, according to the Federal Security Service branch in the province. Artillery shells and other munitions were stored at the site, state-run Channel One reported.
Two firefighters were killed and seven military personnel were injured, Defense Ministry spokesman Alexei Kuznetsov said.
Some 3,000 civilians were evacuated from nearby homes, Ulyanovsk provincial governor Sergei Morozov said, according to Russian news agencies Interfax, ITAR-Tass and RIA Novosti reported.
Both President Dmitry Medvedev and Prime Minister Vladimir Putin showed concern about the blasts. Medvedev directed the military and emergency services to take "all the necessary measures" to deal with the emergency, the Kremlin said. Putin issued similar instructions, Interfax cited his spokesman Dmitry Peskov as saying.
Hours after the blasts and fire began, Morozov said more than 40 workers were safe. "These are precisely the people considered to be missing," Morozov told Channel One by telephone. He had said earlier that 35 people were missing.
The 43 military personnel who took refuge in the bomb shelter emerged with the help of rescuers after firefighters "partially localized" the blaze, the provincial government said on its Web site.
State-run RIA Novosti later cited governor's aide Sergei Davydov as saying 11 civilians and military personnel were still unaccounted for, but that it was possible they were with relatives.
Morozov said the fire was out, but that isolated explosions continued late Friday, Interfax reported. It quoted the governor as saying six people remained hospitalized.
Several explosions and fires have occurred at munitions storage facilities in the former Soviet Union in recent years. There has been no indication of terrorism in the conflagrations.
Artillery shells and other ammunition at a storage facility west of Ukraine's capital, Kiev, exploded when a forest fire got too close in August last year, and a fire and explosions at a munitions depot in southern Ukraine in 2004 killed five people. It took days to put the blaze out.
A fire at a Soviet-era military base in Kagan, Uzbekistan, spread to an ammunitions depot in July 2008, igniting a series of explosions that killed three people and injured 21 others.
Associated Press Writer David Nowak contributed to this report.