Authorities in a Russia say cleanup efforts are well underway after an exploding meteor's shock wave shattered an estimated 200,000 square metres of windows.

The Chelyabinsk city administration said in a statement on Sunday that nearly 60 per cent of the city's broken windows had been replaced.

Tens of thousands Chelyabinsk residents were out in droves Saturday to help clean-up the damage after Friday's meteor explosion over the area.

As many as 24,000 people, including many volunteers, began cleaning up the mess from Friday’s shocking event that shattered windows in more than 4,000 buildings and injured 1,200 people. Most of the people were injured from the flying glass.

The explosion was estimated to have the force of 20 atomic bombs.

By Saturday, 40 people remained in hospital, two in serious condition, local media reported.

The region’s governor Mikhail Yurevich estimated the damage from the explosion to be around $33 million. Yurevich said the windows would be replaced in a week, but with frigid temperatures, a week is a long wait.

The temperature was -12 C in Chelyabinsk by midday Saturday.

Volunteers not only helped repair buildings, but also collected donations of warm clothing and food.

People began to put up plastic sheeting and boards to cover the holes in the broken windows, the governor’s office said. Representatives from glass companies from the surrounding area were brought in to help.

As people got to work, they also took the time to find some humour in their situation, with jokes making the rounds among residents and online.

One popular joke had residents speculating that inhabitants of the meteor were terrified to see Chelyabinsk approaching.

Chelyabinsk can be a harsh place. It’s the town nicknamed Tankograd because it once produced the famous Soviet T-34 tanks. Temperatures in the region regularly dip to -30 C. The broader region is also home to a nuclear waste disposal facility, as well as a chemical weapons disposal plant.

The city is a place where people always seem bitter with each other," said music teacher Ilya Shibanov. But the meteor "was one of the rare times when people started to live together through one event."

"For most people, it's a good excuse for a joke," he said.

Meanwhile 80 kilometres west in the town of Chebarkul, divers scoured the bottom of an icy lake while they searched for meteor fragments. It is believed that fragments have fallen in the lake, leaving a 20-foot-wide hole.

Irina Rossius, a spokesperson for the Emergency Ministry, told Russian news agencies that nothing has been found in the lake.

In San Francisco, residents witnessed what appeared to be a meteor Friday night and Cuban media reported spotting a similar meteorite explosion earlier in the week.

Also on Friday, Asteroid 2012 DA14 came within 27,600 kilometres of the Earth, closer than some satellites orbiting the planet. Scientists said the asteroid measures around 50 metres wide.

McMaster University assistant professor of physics and astronomy Laura Parker told CTV News Channel on Saturday that the series of events, while dramatic, are actually just normal elements of the solar system.

“These objects are all connected. They’re all small solar system objects,” Walker said.

“Meteors happen every night,” she continued. “These dramatic events that get labelled fire balls -- which are particularly bright meteors -- are less common but even those happen every single night.

“It just so happens by coincidence that many people have observed fire ball events this week, but they’re happening all the time.”

Parker added that while Asteroid 2012 DA14 appeared to come very close to Earth, researchers discovered it over a year ago and have known since then that it posed no threat to the planet.

“We knew a long time ago that it posed no risk to the Earth,” she said.

With files from The Associated Press