An Iranian soldier shot to death three policemen and a fellow soldier at a police station in southern Iran, local media reported Sunday.
The incident took place near the town of Bampour, in the restive Sistan and Baluchistan province.
"The shooter was immediately arrested by a number of other station staff, he is currently in custody and a judicial investigation has been started," provincial officials told local media.
"The motive of the killer is being investigated, but preliminary investigations show that the cause and motive of the murder was a personal dispute with one of [the attacker’s] colleagues, who, with the intervention of other personnel, tried to disarm him," Hussein Mir Ezhar told the semi-official Tasnim news agency.
Iran’s Sistan and Baluchistan province borders Pakistan and Afghanistan. It is one of Iran’s poorest provinces and home to a Sunni Baluch minority estimated to number up to two million people.
Zahedan was the scene of a violent crackdown on September 30 in which security forces killed 92 people, including 12 children, according to IranWire sources. Four security officers were also killed that day – which was dubbed Zahedan’s Black Friday.
The incident was the deadliest single episode to date in the widespread protests triggered by the September 16 death of 22-year-old Mahsa Amini in the custody of Tehran's morality police.
Security forces, including Basij paramilitary volunteers with the Revolutionary Guard, have violently cracked down on the demonstrations, killing over 300 people, including 41 children, according to the Oslo-based Iran Human Rights.