DOGO NAHAWA, Nigeria— The attackers came at night and surrounded this small farming village, firing shots in the air to scare residents from their homes. Men, women and children were hacked with machetes as they rushed out. Several houses were set on fire with residents still inside.

Details are beginning to emerge from attacks Sunday on four villages in central Nigeria, where witnesses say members of the predominantly Muslim Fulani ethnic group targeted villages that were home to members of the mostly Christian Berom ethnic...