A patrol party was targeted by the Naxals, they said, adding that the seven injured men -- five from the Central Reserve Police Force (CRPF) and two from the Jharkhand police -- were airlifted to Ranchi.
The blast took place around 2 pm near the Pipardhaba village of Balrampur district in Chhattisgarh, bordering Jharkhand, followed by an exchange of fire between the Naxals and the security men, the sources said.
The joint team of troops was out for an anti-Naxal operation when the blast was triggered.
Additional forces from nearby areas were rushed to the area and the firing had stopped, the sources said.
The CRPF men belonged to the 62nd battalion, they added.
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