(Xinhua) -- Four security men were killed in northwestern Pakistan's tribal area on Tuesday, local TV channels reported. Some security men patrolling in Khyber Agency were ambushed by unknown gunmen. Resultantly four security men were killed and several others injured, said the report. The government last Friday suspended its security operation against suspected militants in Khyber Agency to allow tribal elders to meet militants and conduct peace talks. The security forces launched a major operation against local militant groups in Khyber Agency on June 28 and took control of the area.