A powerful explosion has damaged a building in the center of the Czech capital, Prague, injuring up to 40 people. Authorities say they believe some people are buried in the rubble, according to a report of the Associated Press. Police spokesman Tomas Hulan says it is not certain what caused the blast in Divadelni Street, but it was likely a natural gas explosion. The street was covered with rubble and has been sealed off by police who have also evacuated people from nearby buildings and closed a wide area around the explosion site. Zdenek Schwarz, head of the rescue service in Prague, says up to 40 people have been injured. Windows in buildings located hundreds of meters from the blast were shattered, including some in the nearby National Theater.