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.