Manama: Bahrain tightened security measures in some parts of the country following a prison break, while a probe by the interior ministry is underway, officials said on Saturday. The incident occurred on Friday night, Xinhua news agency reported. A local media report said that around 20 prisoners had escaped, adding that they managed to seize a bus and get away after assaulting warders and police and injuring several of them. In a statement, the ministry said that the authorities have set up check points and roadblocks to catch the escaped inmates. "The interior minister has ordered the formation of an investigation committee to determine the circumstances and who was responsible in order for legal proceedings to be filed," the statement added.