At least four soldiers were killed and three others injured at a bomb explosion at their vehicle in Pakistan's northwest tribal area of Mohmand Agency on Saturday morning, officials said. Inter Services Public Relations, the mouthpiece of Pakistan army, said in a statement that the incident happened when a vehicle carrying security personnel was hit by a landmine in Atmanzai area of Mohmand Agency, a tribal region at Pakistan- Afghan border. Media reports said that the troops were on their way to conduct a search operation in the area on an intelligence tip-off when they came under attack on the way. The injured people have been shifted to a nearby hospital. No group has claimed responsibility for the attack yet.