At least 40 people are reported to have been killed by Islamist militants near the northern Nigeria town of Monguno.
The militants waited until villagers had finished praying before singling out the men and shooting them, a resident told the BBC. The women are said to have been spared.
The killings are said to have happened two days ago, but details are only now emerging because of bad communications.
Monguno, in Borno state, was recently recaptured from Boko Haram militants. At least 23 people died in the town last month after a confiscated Boko Haram bomb exploded during celebrations to mark the successful military operation against the Islamist group.
There is no mobile phone coverage in the village where the shooting occurred, but a resident of the nearby Monguno town told the BBC Hausa service that he had heard gun shots and saw the village on fire.
“They were praying in the mosque when Boko Haram attackers descended on the village. They waited till they finished the prayers. They gathered them in one place, separated men from women and opened fire on them,” he said.
“Many died, some escaped. They then set fire on the village. I saw five victims with bullet wounds who managed to escape. They were brought to our town [Monguno] on wheelbarrows, before they were transferred to vehicles that took them to hospitals.”
The politician representing the area, Mohammed Tahir Monguno, said jihadist fighters who had recently been flushed out of their stronghold in the Sambisa forest had settled in these villages close to Lake Chad.
He said that before the attack, he had notified the military of the jihadists’ presence, warning that the villages were not safe.