A Russian soldier on Friday opened fire on fellow troops at a Siberian military base, killing eight and wounding another two, officials said, blaming the attack on a possible "nervous breakdown".
"The serviceman who opened fire has been detained," the ministry said in a statement, quoted by Russian news agencies.
The incident took place at a military base in the Chita region in eastern Siberia.
"The actions of the serviceman could be the result of a nervous breakdown caused by personal circumstances not connected to his military duty," the defence ministry said, citing preliminary information.
The wounded were hospitalised, the ministry said, adding that their injuries were not life-threatening.
A commission chaired by Deputy Defence Minister Andrei Kartapolov was on its way to the base.
A defence ministry spokesman declined to immediately comment when reached by AFP.
Brutal hazing rituals were a major problem in the Russian army in the 1990s but this has significantly improved in recent years.