Residents say gunmen kill at least 20 people in mining village of Nigeria's Zamfara state

Gunmen have killed at least 20 people in an attack in a gold mining village in Nigeria's northwestern Zamfara state, residents and Amnesty International said.

Details on a possible motive for the attack were not immediately known, but Zamfara state has grappled with kidnappings for ransom by armed gangs, who also target security forces.

Ismail Hassan, a resident, told Reuters that gunmen in their hundreds opened fire on miners on Thursday afternoon, and a firefight ensued, with over 20 people dead in the mining village of Gobirawa Chali in the Maru local government area of Zamfara state.

Another resident, Isah Ibrahim, said they had recovered 21 bodies following the attack and that several were injured.

Amnesty International said in a statementthat  the gunmen went house-to-house in Gobirawa Chali, killing over 20 people.

Armed gangs of men have killed and kidnapped hundreds across northwest Nigeria over the past two years, typically operating from remote forests. The country's thinly stretched armed forces have struggled to secure the large, remote regions.

Nigeria's military is stretched by insecurity across the country, including an Islamist insurgency in the northeast, deadly farmer-herder clashes in the central belt and clashes with separatist movements in the south.