Six security men and two civilians were killed Friday evening when the Maoists ambushed a passenger bus near the Kathmandu Valley, security sources said Saturday. The fresh attack came less than a week after a Maoist landmine blew up a passenger bus in southern Nepal, killing 38 persons including three security men. There was widespread condemnation of the attack, DPA reported. Security sources in the Nepalese capital said Maoists attacked the bus on a highway in Kabre district about 60 kilometres north east of the capital Friday evening. Three others riding on the bus were injured and were brought to the capital for treatment, security sources said. They said security personnel were presently engaged in search operations to flush out the rebels. The Maoists seeking to set up a communist republic in Nepal launched an insurgency in February 1996. Over 11,500 persons are estimated to have been killed in the insurgency so far.