A Maoist was on Tuesday killed while three security personnel,including a CRPF commandant,were injured in an encounter between the two sides in the district. On information that the ultra-left wing guerrillas had gathered near the village,about 80 km from Ranchi,the police rushed to the spot around 4 am,SP Anup Birtheray said. In the ensuing encounter,CRPF Commandant R R Mishra,a CoBRA jawan and a district police man suffered injuries,and were admitted to a hospital,he said. One Maoist was killed and the retreating rebels fled with the body,police added.