At least three persons, including two Pakistani soldiers, were killed on Tuesday when a suicide bomber blew up an explosive-laden car near an army post in North Waziristan, the first such attack in the area since the military launched an all-out offensive against the Taliban.The incident happened in Spinwarm area of North Waziristan where the Pakistani military on June 15 launched the major offensive to drive out local and foreign militants from the region. A security official said that the blast occurred 100 metres from a security post when the vehicle was stopped by Pakistani troops.