LAGOS, Nigeria — Suspected Muslim extremists kidnapped about 100 girls Tuesday from a school in northeastern Nigeria, less than a day after militants bombed a bus station and killed 75 people in the capital – a surge of violence that raised new doubts about the military’s ability to contain an Islamic uprising.

With an 11-month-old state of emergency in three northeastern states failing to bring relief, the attacks are increasing calls for President Goodluck Jonathan to rethink his strategy in confronting the biggest threat to the security of Africa’s most populous nation.

The attacks by the Boko Haram terrorist network have killed more than 1,500 people in this year alone, compared with an estimated 3,600 dead between 2010 and 2014.

In the latest attack, gunmen killed a soldier and a police officer guarding a school in Chibok on the edge of the Sambisa Forest and abducted the teenage girls after midnight, according to authorities.

Some of the girls escaped by jumping off the open truck as it was moving slowly along a road, according to an official who spoke on condition of anonymity because he was not authorized to talk to reporters.

Islamic extremists have been abducting girls to use as cooks and sex slaves.

All schools in Borno state were closed three weeks ago because of stepped-up attacks that have killed hundreds of students in the past year. But the young women – aged between 16 and 18 – were recalled to take their final exams, a local government official said.

Boko Haram, whose name means “Western education is forbidden,” has targeted schools, mosques, churches, villages and agricultural centers in assaults that are increasingly indiscriminate. The insurgents have also made daring raids on military barracks and bases.

The report of the abductions came as officials were still dealing with the aftermath of Monday’s bombing at the Abuja bus station that killed 75 and wounded 141, just miles from Nigeria’s seat of government. The attack also was blamed on Boko Haram.