The death toll from a rocket explosion at a Russian missile test range rose to five on Saturday, after initial reports listed two dead.

Defense officials have nonetheless shut down fishing, swimming and shipping traffic in a portion of the White Sea.

The explosion happened Thursday during tests on a liquid propellant rocket engine at an arctic naval range in Nyonska run by state nuclear company Rosatom, the BBC reported.

In addition to the five dead, three staffers suffered serious burns. A nearby kindergarten was also reportedly damaged, and more than 9,500 people were evacuated.

Officials in the nearby city of Severodvinsk reported a 40-minute spike in radiation levels to 2 microsieverts per hour. Normal levels are around 0.11 microsieverts/hour.

While the levels were not high enough to cause sickness, according to the BBC, locals reportedly rushed to pharmacies for iodine, depleting stocks in Arkhangelsk and Severodvinsk.

Severodvinsk officials initially reported the radiation spike on its website, but later deleted the statement, saying “this incident comes under the authority of the defense ministry.”

The defense ministry said “there have been no harmful chemicals released into the atmosphere, the radiation levels are normal,” the BBC reported.

Rosatom engineers were working on an “isotope power source” for the rocket propulsion system at the time of the explosion, according to the BBC.