Aug. 10 (UPI) -- Five employees of Russia's nuclear corporation Rosatom have died and three have been treated for burns after a liquid-propellant engine exploded during a test.
The explosion occurred as the engineering and technical team worked on the "isotope power source" for the propulsion system Thursday.
It caused a radiation spike around the military testing site in the Arkhangelsk region that drove radiation levels up to 20 times the normal level in the nearby city of Severodvinsk for about half an hour.
The company confirmed the employee deaths and injuries in a Facebook statement Saturday.
"As a result of the accident, five employees of the State Atomic Energy Corporation Rosatom were killed during a test at a military training ground in the Arkhangelsk region," the company said. "Three of our colleagues were injured and burned. The injured were delivered to a specialized medical institution."
"We express our deepest condolences to the families and friends of the victims," the company added. "Their families will be assisted and supported."
Rosatom's description of the incident could indicate it was testing the nuclear-powered cruise missile that Vladimir Putin mentioned in a speech last year, but it remains unclear what type of 'experimental' missile or jet engine was tested.
Russia's defense ministry confirmed the explosion Thursday, initially saying that two were killed and six injured in the failed test, indicating that three of those first reported injured have since died.