MOSCOW — At least two service members were killed and four others injured on Thursday after an explosion at a test range near Arkhangelsk, located on Russia’s northern coastline, the Russian Defense Ministry told local news agencies.

The Defense Ministry told Interfax news agency that “no harmful substances were emitted into the atmosphere and the radiation levels are normal,” after rumors spread of radiation hazard in the area.

The ministry said the explosion was caused during the test of a liquid-fueled rocket engine. It was not immediately clear which missile design uses such an engine, as many military missiles rely on solid fuel engines.

The Defense Ministry did not specify where exactly the explosion took place, noting only that the site was a military testing ground. Unconfirmed reports in the Russian press placed the explosion near the village of Nyonoksa.

Another unconfirmed report by state-run TASS initially reported the explosion took place aboard a ship.

Defense Ministry officials were not immediately available for comment on the incident.

Flames and smoke rise from the site of blasts at an ammunition depot near the town of Achinsk, Russia, on Monday Dmitry Dub / Reuters

Arkhangelsk region is home to Sevmash, the nation's most important military shipyard, in the city of Severodvinsk. Russia builds nuclear submarines there. The submarines are themselves based further north, in Murmansk region, at the Northern Fleet headquarters of Severomorsk.

Last month, concerns over Russian military nuclear safety spiked when a nuclear-powered submarine caught on fire, killing 14 sailors.

If Thursday’s incident in fact took place on land, it would not be the first time the Russian military has experienced an accident at a storage or testing facility.

On Monday, a major explosion rocked the city of Achinsk in Siberia after a fire detonated a 40,000 shell stockpile of munitions at a military storage facility. The fire, and subsequent explosions, raged for hours before emergency services could extinguish the blaze.

The regional government in Siberia called for all 100,000 residents of Achinsk to prepare for evacuation. So far, the Arkhangelsk government has said it is not planning to evacuate residents after Thursday’s incident.