detonation

Police said in a statement that it was an accidental detonation, not a terrorist attack.

No country other than North Korea is known to have conducted a nuclear detonation for decades.

The last US nuclear test explosion was in September 1992, with a 20-kiloton underground detonation at the Nevada Nuclear Security Site.

But military officials said they suspect there was an issue with the fuse that led to the premature detonation.

The volatile nature of the explosive materials has also hampered the emergency response, officials said, as controlled detonations to render the site safe are also expected in the coming days.