"Suddenly, it was very, very horribly bright,” a local teacher in the Chelyabinsk Region told RIA Novosti. “Not like the lights got turned on, but as if everything was illuminated with unusual white light."

Police and other officials said around 1,200 people had been hurt, including more than 200 children, mostly in the Chelyabinsk Region near the Ural Mountains. By the end of the day, the number hospitalized was 50, according to the Emergencies Ministry. Earlier, at least two people were reported to be in "grave" condition.

The majority of those hurt had suffered cuts from broken glass, but the region's governor said two-thirds of the injuries were very light.

The blast was so powerful that it was detected by 11 of the 45 infrasound stations of the Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO)’s network designed to track atomic blasts across the planet.

Bill Cooke, lead for the Meteoroid Environments Office at NASA's Marshall Space Flight Center, said at a teleconference on Saturday (Moscow time) the object that exploded above Chelyabinsk was, in fact, a “tiny asteroid” measuring about 15 meters in diameter and weighing 7,000 metric tons.

According to the NASA expert, it entered the atmosphere at a shallow angle of about 20 degrees and exploded at the height of about 20-25 km, generating an energy shockwave equal to about 300 kilotons of TNT, or 20 nuclear bombs equal in force to the one dropped on Hiroshima in 1945. The vast part of the energy was absorbed by the atmosphere.

Later, as new information filtered in from monitoring stations around the world, NASA upped its estimates of the object's power, mass and size. An update posted on the NASA site estimates that 500 kilotons of energy was released, that it was 17 meters in size before entering the earth's atmosphere, and that it had a mass of 10,000 tons - making it 30 times more powerful than the Hiroshima bomb.

President Vladimir Putin ordered emergencies officials to provide "immediate" assistance to people affected by the meteorite. Officials said gas supplies were cut off to hundreds of homes in the Chelyabinsk Region as a safety precaution. Some 3,000 residential buildings were also damaged, Chelyabinsk city administration officials said. An estimated 20,000 emergency response workers have been mobilized.

Speaking to journalists on Saturday, Emergencies Minister Vladimir Puchkov commended the teams working on the ground in the areas affected "a great deal of work has already been done, and we are now launching rebuilding work," adding "power, transport, and communications systems are all workign stably."

He also praised Chelyabinsk residents for what he called their restraint, patience and level-headedness.

Also speaking on Saturday, Chelyabinsk Region Governor Mikhail Yurevich said that repair work was well underway and that approximately 100,000 homeowners had been affected.

Background radiation levels reportedly remain unchanged. This was confirmed both by emergencies officials, and by the national nuclear agency, concerned because the area has a fair number of nuclear facilities.

Reports about whether this was one large meteorite or many smaller ones initially varied, but the national space agency, Roscosmos, confirmed by early afternoon that the object had been a single meteorite, a report given earlier by emergency officials.

“Verified information indicates that this was one meteorite which burned up as it approached Earth and disintegrated into smaller pieces,” deputy head of the Russian Emergencies Ministry press office, Elena Smirnykh, said.

Roscosmos stated the meteorite had been moving at a speed of 30 kilometers (18.6 miles) per second.

Officials are trying to determine where the fragments have landed. None have been recovered as of Saturday morning.

The Chelyabinsk governor said one fragment had fallen in a lake in his region, while others have been reported in the Tyumen, Kurgan and Sverdlovsk regions as well. Police said an eight-meter wide crater had been discovered near the Chelyabinsk lake. Radiation levels around the crater were reported to be normal.

A spokeswoman for the Russian emergencies ministry, Irina Rossius, said on Saturday a group of six divers is preparing to plunge into the Chebarkul Lake to search for meteorite fragments. The dive is scheduled to last about four hours.

Early in the day, emergency officials in neighboring Kazakhstan said they were searching for two unidentified objects that reportedly fell in the country's Aktobe region. But no meteorite fragments had been found by Friday evening, local time, leading to speculation that if meteors had entered the Earth's atmosphere over the Central Asian country they had been vaporized before making impact.

The European Space Agency (ESA) said there was no link between the meteorite and the 2012 DA14 asteroid which is due to pass close by the Earth later on Friday. NASA also said there was no connection because the asteriod and the "Russian meteorite" are on "very different paths."

Russian Prime Minister Dmitry Medvedev, speaking at an economic forum going on in Siberia's Krasnoyarsk region, called the meteorite “a symbol of the forum.”

“I hope that there will be no serious consequences, but it is a demonstration that it is not only the economy that is vulnerable, but our planet as well,” he said.