The meteor entered the atmosphere about 10:20 p.m. EST Thursday at a hypersonic speed of at least 33,000 mph, the Russian Academy of Sciences said. NASA estimated its speed at about 40,000 mph and the energy released in the hundreds of kilotons.
"There was panic. People had no idea what was happening," said Sergey Hametov of Chelyabinsk, about 930 miles east of Moscow.
According to city officials, 3,000 buildings in Chelyabinsk were damaged.
The Interior Ministry said about 1,100 people sought medical care after the shock wave and 48 were hospitalized. Most of the injuries were caused by flying glass, officials said.
There was no immediate word on any deaths or anyone struck by space fragments.
Some meteorite fragments fell in a reservoir outside the town of Chebarkul, the regional Interior Ministry office said. The crash left a 26-foot crater in the ice.
Meteors typically cause sizeable sonic booms when they enter the atmosphere because they are traveling so much faster than the speed of sound. Injuries on the scale reported Friday, however, are extraordinarily rare.
Meteroids are small pieces of space debris - usually parts of comets or asteroids - that are on a collision course with the Earth. They become meteors when they enter the Earth's atmosphere. 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.
NASA said the Russian fireball was the largest reported since 1908, when a meteor hit Tunguska, Siberia, and flattened an estimated 80 million trees. Chelyabinsk is about 3,000 miles west of Tunguska. The Tunguska blast, attributed to a comet or asteroid fragment, is generally estimated to have been about 10 megatons.
Scientists believe that a far larger meteorite strike on what today is Mexico's Yucatan Peninsula may have been responsible for the extinction of the dinosaurs about 66 million years ago.