Four security personnel were killed and six others injured in a land mine blast today at Balrampur district, official sources said, PTI reported. "Four policemen were killed and six injured in a powerful landmine blast, triggered by Maoists in Chunchuna village under Samri police station area bordering Jharkhand," police sources told PTI. The policemen were travelling in a jeep from Samri to Kusmi when the explosion took place, sources said. Additional forces have been rushed to the spot, they added.