Kabul. A deadly blast in the west of Kabul that left at least three people dead has marked the formal handover of nationwide security from the US-led NATO coalition to Afghan forces.The handover of responsibility on Tuesday is a significant milestone in the nearly 12-year war against Taliban and other armed groups and marks a turning point for American and NATO military forces, which will now move entirely into a supporting role.  It also opens the way for their full withdrawal in 18 months.The ceremonial handover was, however, marred by an explosion that targeted the convoy of Mohammed Mohaqiq, a prominent ethnic Hazara lawmaker. Mohaqiq is said to have survived the blast.General Mohammad Zahir, chief of the Kabul Criminal Investigation Division, said three people were killed by the bombing and another 30 were wounded - including six bodyguards."The roadside bomb targeted the Mohaqiq convoy, but he safely passed. One of his vehicles was damaged,” Zahir said.The blast came as hundreds of local and international officials gathered on the capital’s outskirts to mark the beginning of the final phase of security transition to Afghan forces across the nation.Afghan President Hamid Karzai announced the formal handover. "Our security and defence forces will now be in the lead,” he said in a speech."From here, all security responsibility and all security leadership will be taken by our brave forces.”Fogh Rasmussen, the NATO secretary-general, said the International Security Assistance Force (ISAF) would help militarily if and when needed but will no longer plan, execute or lead operations.  "The main effort of our forces is shifting from combat to support,” he said in speech during the ceremony. "By the end of 2014, our combat mission will be completed. At that time, Afghanistan will be fully secured by Afghans,” he saidFollowing the handover, Afghan forces will now have the lead for security in all 403 districts of Afghanistan’s 34 provinces.