A meteor streaked across the sky above Russia's Ural Mountains this morning, causing sharp explosions and injuring more than 400 people, many of them hurt by broken glass.
Fragments of the meteor fell in a thinly populated area of the Chelyabinsk region, the emergency ministry said in a statement.
More than 400 people sought medical treatment after the blasts, according to interior ministry spokesman Vadim Kolesnikov, and at least three were in a in serious condition in hospital.
Many of the injuries were from glass broken by the explosions.
Sergey Hametov, a resident of Chelyabinsk, about 900 miles east of Moscow, said: "There was panic. People had no idea what was happening. Everyone was going around to people's houses to check if they were okay.
"We saw a big burst of light then went outside to see what it was and we heard a really loud thundering sound."
Mr Kolsenikov said about 6,000 square feet of a roof at a zinc factory collapsed.
Reports conflicted on what happened in the clear skies. A spokeswoman for the emergency ministry, Irina Rossius, said there was a meteor shower, but another ministry spokeswoman, Elena Smirnikh, was quoted by the Interfax news agency as saying it was a single meteorite.
Amateur video broadcast on Russian television showed an object speeding across the sky about 9.20am local time, leaving a thick white trail and an intense flash.
The meteor hit less than a day before the asteroid 2012 DA14 is to make the closest recorded pass to Earth of an asteroid - about 17,150 miles.
Donald Yeomans, manager of US Near Earth Object Programme in California, said he thought the event was probably "an exploding fireball event."
"If the reports of ground damage can be verified, it might suggest an object whose original size was several meters in extent before entering the atmosphere, fragmenting and exploding due to the unequal pressure on the leading side vs. the trailing side (it pancaked and exploded)," he said.
"It is far too early to provide estimates of the energy released or provide a reliable estimate of the original size," he added.
The European Space Agency, in a post on its Twitter account, said its experts had determined there was no connection with the asteroid.
Small pieces of space debris - usually parts of comets or asteroids - that are on a collision course with the Earth are called meteoroids. When meteoroids enter the Earth's atmosphere they are called meteors. Most meteors burn up in the atmosphere, but if they survive the frictional heating and strike the surface of the Earth they are called meteorites.
The dramatic events prompted an array of reactions from prominent Russian political figures.
Prime Minister Dmitry Medvedev, at an economic forum in the Siberian city of Krasnoyarsk, said the meteor could be a symbol for the forum, showing that "not only the economy is vulnerable, but the whole planet."
Vladimir Zhirinovsky, the nationalist leader noted for vehement statements, said "It's not meteors falling, it's the test of a new weapon by the Americans," the RIA Novosti news agency reported.