ABUJA, Nigeria (AP) — Security forces rescued 14 out of at least 20 students abducted from a university in northwestern Nigeria and were searching for the remaining captives, school authorities said Monday

Gunmen attacked the school in the hard-hit Zamfara state’s Bungudu district last week and fled with the students and some workers in the first mass school abduction in the West African nation since President Bola Tinubu took office in May.

Such abductions of students from schools are common in Nigeria’s northwest and central regions where armed groups often take people hostage in exchange for huge ransoms which analysts have said help them to buy guns and sustain their operations.

The 14 students from the Federal University Gusau were rescued alongside two other people, a statement from the university said, without further details about when they were freed or the nature of the rescue operation.

“The sad and unfortunate incident has indeed thrown the University community into serious tension and apprehension,” the statement said, adding that security forces were “doing their best” to rescue the remaining students. It also said steps were being taken to boost security around the university.

The latest attack poses a new challenge to Tinubu who extended the ruling party’s reign with his election victory after promising to solve the country’s security crisis. It adds to growing pressure from the opposition and activists who have accused Tinubu of not doing enough to guarantee security.

Armed groups have been carrying out violent attacks in many remote communities, often taking advantage of the inadequate security presence in those areas.

While condemning the abduction in a statement issued by his office on Sunday, Tinubu said his government is “determined to ensure that educational institutions remain sanctuaries of knowledge, growth, and opportunity, and totally free from the menacing acts of terrorists.”