The Katyn massacre was the mass murder of thousands of Polish military officers, policemen, intellectuals and civilian prisoners of war by the Soviet NKVD in 1940. Those killed included generals, colonels, majors, captains, professors, physicians, lawyers, engineers, teachers, writers and journalists. In 2010, the Polish President and many other high-ranking officials were killed when their plane crashed in Russia while traveling to mark the 70th anniversary of the Katyn massacre. The commemoration events were split due to political conflicts between the Polish government and president.