Early morning bombings, including a blast that killed six when it struck a minivan of workers in southern Baghdad, continued Monday. The deaths come as Iraqi and US officials plan a security crackdown following al-Qaida's vow to carry out "major attacks" after the death of terrorist kingpin Abu Musab al-Zarqawi. Officials hope his death will slow sectarian violence. President Bush on Monday began a summit at Camp David to discuss a new strategy for Iraq with top advisers. He is also set to talk with Iraq's Prime Minister Nouri al-Maliki on Tuesday. Together they hope to set a solid agenda for addressing security and repairing infrastructure like Iraq's electricity system that has led to dissatisfaction with US forces.