Two people were killed and a nearby city reported a spike in radiation levels when a rocket engine blew up at a testing site in northern Russia on Thursday, forcing authorities to shut down part of a bay in the White Sea to shipping.

The brief spike in radiation reported by authorities in the nearby city of Severodvinsk, inhabited by 185,000 people, apparently contradicted the defense ministry, which had earlier been quoted by state media as saying radiation was normal.

RIA news agency quoted the defense ministry as saying no dangerous substances had been released into the atmosphere by the explosion of what it called a liquid-propellant rocket engine in the Arkhangelsk region. In addition to the two deaths, it said six people were injured in the blast.