More than 1,000 people have been injured after a meteor streaked across the sky and exploded over Russia's Ural Mountains with the power of an atomic bomb.
Some meteorite fragments fell into a reservoir outside the town of Chebarkul.
The crash left an eight-metre-wide crater in the icy lake.
The meteor - estimated to be about ten tonnes - entered the Earth's atmosphere at a hypersonic speed of at least 54,000kph.
It shattered into pieces about 30-50km above the ground, the Russian Academy of Sciences said in a statement.
It released the energy of several kilotons above the Chelyabinsk region.
The Interior Ministry said about 1,100 people sought medical care after the explosions and most were injured by shards of glass.
There was no immediate word on any deaths or anyone struck by space fragments.
Residents on their way to work in Chelyabinsk heard what sounded like an explosion, saw a bright light and then felt a shockwave, according to a Reuters correspondent in the industrial city 1,500km east of Moscow.
The meteorite raced across the horizon, leaving a long white trail in its wake, which could be seen as far as 200km away in Yekaterinburg.
Such incidents are rare.
A meteorite is thought to have devastated an area of more than 2,000sq km in Siberia in 1908, smashing windows as far as 200km from the point of impact.
The Emergencies Ministry described today's events as a "meteor shower in the form of fireballs" and said background radiation levels were normal.
It urged residents not to panic.
Chelyabinsk city authorities urged people to stay indoors unless they needed to pick up their children from schools.
They said a blast had been heard at an altitude of 10,000 metres, apparently signalling it occurred when the meteorite entered Earth's atmosphere.