Two soldiers in Azerbaijan shot dead four fellow servicemen and then killed themselves on Thursday at a military base in the former Soviet republic, the defence ministry said on Friday.
The ministry said two other soldiers were wounded but that the motive behind the shooting was not clear. It gave no further details.
The opposition Baku daily Azadlig reported that the shooting took place in western Dashkesan region of Azerbaijan, a tightly-controlled mainly Muslim country that exports oil and gas from reserves in the Caspian Sea.
The newspaper said the unit's commander was among the dead but the defence ministry declined to comment on the report.
Analysts say reform of the military has failed to keep pace with huge increases in defence spending on the back of oil revenues aimed at tipping the balance in the festering conflict over the Armenian-backed breakaway region of Nagorno-Karabakh.
In a 2008 report, the International Crisis Group thinktank said that corruption, nepotism and mistreatment were common in the conscript army.