The land mine was allegedly laid by the CPI (Maoists), sources said.
DIG Vipul Shukla said an assistant commandant Gengte, Havildar Nitesh Pandey, Gopal Yadav and Deepak Singh of the para-military force sustained injuries in the incident.
All the injured have been shifted by helicopter to Ranchi for better treatment, he said.
The incident occurred in course of an anti-Naxal operation in the foothills of Budha Pahar -- a suspected strong base of the Naxals.
As soon as they reached the foothills, an explosion took place, injuring the security personnel who were cordoning off the Budha Pahar following an incident of abduction of some villagers in adjoining Garwah district.
Budha Pahar borders adjacent districts such as Garwah, Gumla as well as the state of Chattisgarh.
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