Emergency workers are continuing to search an office building in the Czech capital in Prague after a powerful explosion earlier today.
Several people are missing and authorities believe there is a possibility that people could be buried under the rubble.
Pavlina Adamcova, a spokeswomen for the fire service, said sniffer dogs were being used to help the search.
Sniffer dogs searching a building after a strong blast in central Prague have not yet found anyone at the scene.
Earlier, a fire services spokesman said that some people could be trapped under the rubble.
Two people are believed to be missing, but they may have left before the explosion, Czech newspaper Ceskenoviny reports, citing a police spokesman.
An eyewitness has described her shock after the an explosion at a building in the Czech capital of Prague.
Venceslava Sehnotkova told Reuters: "I was sitting quietly in my flat, making coffee. Then there was an incredible explosion. I thought the building would collapse. I looked out the window, and there was only dust everywhere".
Up to 40 people are believed to have been injured in the blast which is suspected to have been caused by gas, a police spokesman has said.
Emergency services are searching the building - which belongs to the Czech Air Navigation Services company - for people who may have been trapped.
In a statement, the Prime Minister of the Czech Republic Petr Necas said he was "deeply hit by the tragedy of the gas explosion", the Associated Press reports.
It is not certain what caused the blast in Divadelni Street in the central Prague but it was likely to be a natural gas explosion, police spokesman Tomas Hulan said.
Emergency services are attending to the scene of a powerful explosion in central Prague.
Zdenek Schwarz, the head of the rescue service, has said that up to 40 people have been injured.
One eyewitness said: "There was glass everywhere, some people shouting and crying".
A police spokesman said a blast in the Czech capital Prague was probably caused by gas and that there had been about 15 people in the building.
There have not been reports of any deaths, a fire department spokeswoman said.
The explosion, close to Prague's National Theatre, was heard as far as Prague Castle about a mile away.
Windows in neighbouring buildings were blown out, including Prague's landmark Cafe Slavia.
The head of the rescue service attending an explosion in central Prague has said that up to 40 people have been injured.
Police have said that people are also believed to be buried under rubble, the Associated Press reports.
Anna Zamejc, a freelance journalist, who lives near the scene of an explosion in the old city of the Czech capital Prague, reports that witnesses have said that flats at the explosion site were "totally destroyed".
At least 13 people have been injured after a powerful explosion damaged a building in the centre of the Czech capital Prague.
A powerful explosion has damaged a building in the centre of the Czech capital Prague, the Associated Press reports.
Police spokesman Tomas Hulan said it is not immediately clear what caused the blast and it is believed some people are buried in the rubble.
At least 13 people have been injured, fire service spokeswoman Pavlina Adamcova said.
Windows in buildings located hundreds of metres from the blast were shattered, including some in the nearby National Theatre.