Fleeing residents say Boko Haram extremists have kidnapped about 40 boys and young men in northeast Nigeria, and an intelligence officer says the insurgents killed scores of soldiers in an attack on a multinational military base.

Farmer Bulama Malam says the militants came to their remote village of Malari on Friday, urged people to come out and listen to a sermon but instead shot some of them and hand-picked "very young and able-bodied" males aged 12 to 25.

An intelligence officer says the insurgents Saturday nearly overran the Multinational Joint Task Force base at Baga on Nigeria's northeast border with Chad. He spoke on condition of anonymity because he isn't authorized to speak to reporters.

Boko Haram fighters have kidnapped hundreds of girls and boys in the past year.