The violence comes as the top U.S. commander in Iraq is warning U.S. and Iraqi casualties are likely to rise as the military struggles to carry out its goals. General David Petraeus spoke Thursday in Washington.

Gen. David Petraeus: “The situation in Iraq is, in sum, exceedingly complex and very tough. Success will take continued commitment, perseverance and sacrifice, all to make possible an opportunity for the all-important Iraqi political actions that are the key to long-term solutions to Iraq’s many problems. Because we are operating in new areas and challenging elements in those areas, this effort may get harder before it gets easier.”