A powerful explosion in the Czech capital, Prague, has injured at least 20 people, causing police to seal off a tourist area and evacuate buildings.
Police say the cause of the blast on Divadelni Street is not yet clear but speculate it may have been caused by a gas leak. It shattered some windows in the nearby National Theater. One report said it could be heard as far away as Prague Castle, a kilometer and a half across the Vltava River.
Officials say some people may still be trapped in the building where the explosion took place.