The incident took place at Nadiyauna village late last night and the two men killed were brothers, Deep Nagar police station SHO Mohammad Shuzauddin said.
The son of one of them, who was present at the spot, escaped unhurt and lodged a complaint with the police.
As per the FIR lodged with the police, the incident occurred when strongmen of the sand mafia came to the two men around midnight when they were asleep at the community hall and ordered them to lift illegal sand which they refused.
The four persons arrested in connection with the incident are among the five named accused and hail from Rangila Bigaha village under Nalanda police station, the SHO said.
Biharsharif Block Development Officer Anjana Dutta assured help to the victims' families.
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