Villagers in northeast Nigeria are saying that Nigerian soldiers shot and killed a teacher and two middle-aged men who had been detained.
The account comes amid accusations that many other people arrested by the military and vigilantes on suspicion of being Boko Haram fighters have disappeared and are feared dead.
Human rights groups accuse Nigeria's military of killing thousands of civilians in the fight against the Islamic extremists.
The military has denied the allegations.
Villagers from Duhu said on Friday that women protested at a military base after soldiers arrested teacher Habu Bello and two other men, Idrisa Dele and Umaru Hammankadi, on Wednesday.
They later found the men's bodies dumped, with bullet wounds. They spoke on condition of anonymity for fear of reprisals from soldiers.
Nigeria's military has been accused of many atrocities including the deaths of thousands of detainees in the northeastern uprising by Boko Haram.
In 2013, reports by The Associated Press and Amnesty International investigations found the military had killed more than 200 civilians and burned down thousands of homes in the northeast fishing community of Baga after a soldier was killed in the town.