A bomb exploded inside the car of former Greek Prime Minister Lucas Papademos in Athens Thursday, leaving him and two Bank of Greece employees with non-life-threatening injuries, the AP reports. The blast was thought to have been caused by a letter bomb; an anonymous official says the explosion occurred when Papademos, 69, who served as prime minister for six months in 2011-2012 and is also a former deputy governor of the European Central Bank, opened an envelope in the car. His driver was also reportedly injured. No group has taken responsibility for the attack, the BBC reports. Militant far-left and anarchist groups have targeted Greek politicians in the past. (More Lucas Papademos stories.)