'Mystery' fireball lights up night sky above California and Las Vegas

A fireball in the skies above California and Las Vegas turned out to be a Russian rocket burning up on reentry.

Startled onlookers speculated the fiery streak was a meteor, with some even suggesting it was a UFO.

But, as ever, the truth was a little more closer to home.

US Strategic Command said the light was caused by a Russian SL-4 rocket body that reentered the atmosphere somewhere above Arizona on Tuesday evening, blazing across the sky as it went.

The streak of light shone brilliantly over California, Nevada and Arizona and was visible for about 25 seconds before appearing to break up in the sky.

Joint Space Command told NBC News they are unsure if the rocket body survived reentry intact.