Eight young men suspected of being ex-militia members from two rival groups were killed early Sunday in a shootout in Lorbia community in Nigeria's southern oil-rich Bayelsa state, their relations and the army said.
Among those killed were five youths belonging to a group led by ex-militia leader Reuben Wilson, who embraced the 2009 government amnesty.
Wilson's 37-year-old younger brother, Benaibi Wilson, died in the clash, the former militia leader said.
Mourners and sympathisers who thronged the home of Wilson on Sunday in Yenagoa, capital of Bayelsa state, were seen wailing over the deaths.
A spokesman of the Joint Task Force in the Niger Delta, Lieutenant Colonel Onyeama Nwachukwu, confirmed that some people died in the clash between two armed groups but declined to give a death toll or further details.
"At about 2:00 am (0100 GMT) today, there was an armed collision between two armed groups at Lorbia in Southern Ijaw Area which led to the death of unspecified number of persons", he said.
"Our troops have carried out a cordon and search operation in the community," he said, recovering items including two AK47 rifles, six AK47 magazines and a speed boat.
The cause of the clash was unknown.
Rival gangs in the region have in the past clashed over money, status or to avenge an earlier bloody attack.
Bayelsa is the home state of President Goodluck Jonathan.
The 2009 amnesty calmed a wave of violence which harmed oil production in the region.