The attack occurred on July 21, near the Siberian town of Angarsk. Two of the detainees have been charged with premeditated infliction of bodily harm leading to death.
Witnesses say the attackers were dressed in dark clothes, carried metal pipes and shouted nationalist slogans during the attack on the environmentalists, who had been camped out at the site for days.
The activists were protesting against the activities of a chemical plant outside Angarsk that processes uranium for the nuclear power industry.
(AP)