File photo: A Cameroonian general stands by a national flag, in Buea, 26 April 2018. AFP
Four troops were searching for a missing colleague on June 1 when they encountered "a group of frenzied villagers", the ministry said in a statement.
They opened fire and killed four women, four men and an 18-month-old girl, it said, describing their reaction as "inappropriate, ill-suited for the circumstances and manifestly disproportionate".
The incident took place in Missong in the Northwest Region, it said, adding that the troops had been detained.
The Northwest and neighbouring Southwest Region are home to a large minority of anglophones in majority French-speaking Cameroon.
After years of chafing at perceived discrimination, anglophone militants declared an independent state in the two regions in 2017, triggering a crackdown by the authorities.
The spiral of fighting has claimed more than 6,000 lives and prompted more than a million people to flee their homes, according to the International Crisis Group (ICG) think tank.
Separatists have targeted police, soldiers, officials and schools, which they deem to be symbols of the state, often carrying out kidnappings.
However, civilians have suffered abuses committed by both sides, according to international NGOs and the United Nations.