Iranian state TV is reporting that a soldier has opened fire on his comrades, killing three and injuring six others.
The Monday report says the incident took place when soldiers were resting at a military base in the town of Abyek, some 62 miles (100 kilometers) west of the capital Tehran.
The report said the assailant was injured after he shot himself and he was taken to a nearby hospital.
The attack happened after higher officers opposed the attacker's request for a transfer to his hometown.
None of the soldiers was identified in the report.
In September, a soldier killed himself after shooting to death three of his comrades.
Military service of up to 24 months is mandatory for men aged 19 and above in Iran.