Military prosecutors and top officers on Thursday pledged a thorough inquiry into one of the most brutal hazing incidents in the Russian military in years – an 18-year-old soldier whose legs and genitals had to be amputated because of beatings and torture by fellow servicemen.

Human rights groups assailed military officials for condoning rampant bullying and warned such crimes would persist until the nation abolishes the draft in favor of an all-volunteer army.

Doctors said Pvt. Andrei Sychev’s legs and genitals were amputated after the New Year’s Eve incident at the Chelyabinsk Tank Academy, in which older soldiers forced him to spend hours in an unnatural crouched position and brutally beat him.

At least seven other conscripts also were beaten, but they sustained less serious injuries, prosecutors said. Russian news agencies said eight servicemen – including several officers – were detained in the city of Chelyabinsk.

Sychev was hospitalized days after the beating, when he was already in critical condition and unable to stand, and investigators were seeking to determine why he was not treated immediately, a prosecutors’ statement said.