Police probe Prague gas blast CZECH police say they will open an investigation into a powerful gas blast that injured 43 people when it ripped through a four-storey building in Prague's historic centre. "Investigators have not yet been able to make it to the scene of the blast, as the rubble is still being cleared and the work could continue until tomorrow," Prague police spokesman Jan Danek told AFP. Danek added that Monday's blast would likely require a lengthy enquiry but denied there were signs pointing to anything but an accident. Czech media reported two people were still hospitalised on Tuesday following the explosion, said to be the most serious of its kind in the Czech Republic in recent years. The blast, which occurred on the ground floor of an office block in a popular tourist area, heavily damaged the building, blew out windows in nearby streets and shook apartment blocks across the Vltava river. Police evacuated 230 people from the area, fearing further gas leaks, and 43 people were injured, mostly with cuts from shattered glass. Two Kazakhs, two Portuguese, one German and one Slovak were among those hurt. The Generali insurer on Tuesday revised up its estimate of damage done to the 19th-century building to 30 million koruna ($A1.48 million). Gas was still turned off on Tuesday in around 20 buildings in the area, home to the ornate National Theatre whose modern section was also damaged by the blast. Another gas blast in February completely destroyed an apartment block in the eastern town of Frenstat pod Radhostem, killing six people including three children. A male resident who was facing eviction for not paying rent is suspected of intentionally causing that blast, in which he died.