Brigadier General Zaw Min Tun, a military spokesman, said on Thursday soldiers rounded up about 275 people and gathered them at a school after a search operation in Rathedaung area's Kyauk Tan village.
Some of the detainees attempted to seize weapons in the early hours of the morning, forcing government forces to fire into a crowd, he claimed, Presstv Reported.
"We warned them verbally. Then we fired warning shots into the air to disperse the group but they didn't move, so shots were fired," media outlets quoted the military official as saying.
According to a preliminary investigation, the spokesman said, six people were killed after the alleged altercation.
Major General Tun Tun Nyi, another military spokesman, said the remaining villagers were still being held at the school and investigated for links to the Arakan Army, a Buddhist rebel group calling for greater autonomy for Rakhine.
Maung Soe Win, chairman of the Mayu Region Development Association, a local community group, said eight people had been brought to hospital in the nearby Zedi Pyin village with gunshots wounds.
The injured people had been detained for two days when one villager with a mental health problem "got up, shouted and ran away in the middle of the night", he said. "Then (security forces) shot the villagers continuously," he added.
The Arakan Army conducted raids on police border posts on January 4, killing over a dozen people. The clashes have added a new, complex dimension to troubles in Rakhine.
Rakhine has been the scene of violence since 2012. The Myanmar military and Buddhist mobs have killed thousands of Rohingya Muslims. Some 800,000 others have fled to neighboring Bangladesh, living in camps in dire conditions.