In the deadliest mass shooting in American history, a gunman killed upwards of thirty people Monday at Virginia Tech University at Blacksburg, Virginia. Spencer Michels reports on the resignations of six Iraqi cabinet members loyal to Shiite cleric Muqtada al-Sadr. Kwame Holman reports on the fight for full voting rights for residents of the District of Columbia. The guests this episode are Juan Cole, Rend al-Rahim Francke, Krishna Guha. Byline: Jim Lehrer, Jeffrey Brown, Spencer Michels, Margaret Warner, Kwame Holman