Radiation levels near the site of a deadly explosion of an apparent nuclear-powered missile being tested in Russia spiked by up to 16 times above normal, according to the country’s weather service.

The Thursday blast on the coast of the White Sea in Nyonska killed five scientists with Russia’s nuclear agency, which later confirmed they were testing new weapons. More victims were hospitalized.

Rosgidromet, the weather monitoring service, said its sensors in Severodvinsk, a town about 20 miles from the test site, registered gamma radiation exceeding background levels by “four to 16 times,” according to the BBC.

One of the sensors registered a level of 1.78 microsieverts per hour, well above the local average of 0.11 microsieverts, but well below dangerous levels.

The levels — which were higher at six out of eight of its stations in Severodvinsk — returned to normal after two and a half hours, the service said.

The Defense Ministry initially said background radiation had remained normal after the accident. Local officials in Severodvinsk initially reported there had been a brief spike in radiation levels, but later insisted they were not above the norm.

Greenpeace has said the levels rose by 20 times.

Russia’s Rosatom nuclear company has said its workers had been providing support for the “isotope power source” of a missile and were thrown into the sea by the force of the explosion.

US experts have linked the incident to the 9M730 Burevestnik nuclear-powered cruise missile, known by NATO as SSC-X-9 Skyfall, which President Vladimir Putin touted earlier this year.

On Monday, President Trump said the US “is learning much” from the explosion and claimed that Washington has “similar, though more advanced, technology.”

Kremlin spokesman Dmitry Peskov on Tuesday did not confirm that the accident was linked to the Burevestnik project, but said Russian research and development in the sphere of nuclear-powered missiles “significantly surpass the level reached by other countries and are rather unique,” according to AFP.

Meanwhile, there were conflicting reports about whether residents were evacuated from Nyonska on Tuesday.

Some residents told local media they were asked to leave their homes Wednesday ahead of planned military exercises. Officials in Severodvinsk appeared to confirm an evacuation order cited by the Interfax news agency.

But other Russian officials dismissed reports of an evacuation, with regional governor Igor Orlov calling them “complete nonsense” — and Interfax quoted the government of Severodvinsk as saying the military had canceled plans to conduct tests in Nyonska.

With Post wires