Officials have raised the death toll to five people in a mysterious August 8 explosion and fire at a military unit in Russia's northwestern Arkhangelsk region, as a string of blasts have rocked Russian military sites in recent days.
"As a result of the accident at a military testing range in the Arkhangelsk region involving a liquid-fuel jet engine, five Rosatom employees died," the state-run nuclear company said on August 10, raising the number of fatalities from the two reported a day earlier.
The statement said three other staff members sustained injuries and burns of varying degrees and are receiving treatment at the hospital.
That the update was released by the state-run nuclear power agency, not the Defense Ministry, added to mounting evidence of some sort of nuclear-related accident at the site.
The Russian Defense Ministry had said a fire broke out after a reaction engine exploded on August 8 "when testing a liquid propulsion system."
Regional authorities said the explosion and fire took place near the town of Nyonoksa, where a navy ballistic-missile test range for nuclear submarines is located.
There have been "no harmful chemicals released into the atmosphere," the Defense Ministry said, adding that "radiation levels are normal."
However, the nearby city of Severodvinsk, some 30 kilometers away, said a "brief spike" in radiation levels was registered after the blast.
"Sensors in Severodvinsk recorded a short-term increase in radiation levels. Currently, the levels have returned to normal," according to a statement on the city's website, citing readings between 11:50 a.m. and 12:30 p.m. local time.
However, that statement was later taken down from the city's website.
Citing data from the Emergency Situations Ministry, Greenpeace said radiation levels had risen 20 times above the normal level in the city.
The Arkhangelsk regional news site 29.ru said that nearly all the pharmacies in the city have been emptied of iodine drops, which are used to protect the thyroid gland from certain types of radiation.
Contacted by telephone by RFE/RL, one pharmacy in Severodvinsk reported being sold out of iodine as of August 8. A second said most of its supplies had been bought up. Neither of the employees who answered the phones would give their names.
Nyonoksa is on the coast of the Dvina Bay of the White Sea in the Russian Arctic, about 40 kilometers west of Archangelsk, a major port used for exporting oil products and coal.
Reuters quoted two U.S.-based nuclear experts as saying they suspected the blast and radiation release occurred during the testing of a nuclear-powered cruise missile that President Vladimir Putin spoke of a year ago.
In separate interviews, the experts asserted that a liquid rocket-propellant explosion would not release radiation.
They said they suspected the incident occurred because of a mishap during the testing of a nuclear-powered cruise missile at a facility outside Nyonoksa.
"Liquid-fuel missile engines exploding do not give off radiation, and we know that the Russians are working on some kind of nuclear propulsion for a cruise missile," Ankit Panda, an adjunct senior fellow with the Federation of American Scientists, told Reuters.
A senior U.S. official told Reuters that the details of the mishap are still unclear, but he expressed skepticism over the official explanation.
"We continue to monitor the events in the Russian far north, but Moscow's assurances that 'everything is normal' ring hollow to us," said the official.
"This reminds us of a string of incidents dating back to Chernobyl that call into question whether the Kremlin prioritizes the welfare of the Russian people above maintaining its own grip on power and its control over weak corruption streams," the official added.
The blast was one of at least three explosions to rock Russian military sites in recent days.
On August 5, one person died and eight people were wounded in a series of blasts at an ammunition depot in the Siberian region of Krasnoyarsk.
The Investigative Committee said it was investigating possible violations at the site during the handling of weapons in connection with the explosions, which prompted a state of emergency in the surrounding region.
On August 9, local authorities said nine people were injured in new explosions at the same site, with authorities saying the blast was “caused by a lightning strike."
The military was also shaken by the deaths of 14 sailors killed in a fire on one of the navy's research submersibles in July 1.
Military and government authorities have given scant details about the incident, which the Defense Ministry said occurred in the Barents Sea and was one of Russia's worst submarine disasters in years.