DAKAR, Senegal — Islamist militants stormed into a girls’ school in northern Nigeria this week, and with many girls still unaccounted for, Nigerians feared their country was experiencing a notorious mass abduction like one that drew worldwide condemnation almost four years ago.

Militants from Boko Haram, the Islamist extremist group behind the earlier kidnappings, raced into the village of Dapchi on Monday in machine-gun mounted trucks and opened fire, witnesses said. As they headed for the Government Girls Science and Technical School, students and teachers fled, some climbing fences to escape.

More than 50 students were still missing, according to state government officials. The local police gave conflicting information to reporters, saying about 100 girls were gone. Late Wednesday, local media outlets reported that the girls had been rescued, but that could not be verified.

During the attack, groups of students ran into the bush and other villages and some headed for their homes on farms far from Dapchi. A few students and residents have told local reporters that some girls were spotted being hauled away by the militants.