A resident in a Niger village says that 200 vehicles with soldiers from Chad and Niger have been seen crossing the border into Nigeria to fight Islamic extremists there.

Adam Boukarna, a resident of Bosso which in Niger across Nigeria's northeast border, said Monday that vehicles have been crossing since Saturday. He said after they all crossed into Nigeria loud detonations could be heard, signaling fighting against Boko Haram members.

Nigeria's neighbors are forming a multinational army to confront Boko Haram.

Niger's government has not publicly confirmed this ground assault. The Chadian military spokesman also declined to comment.

Boko Haram's Islamic uprising has killed about 12,000 people in the nearly 6-year-old Islamic uprising in northeastern Nigeria.