A timeline of abductions from schools in Nigeria

LAGOS, Nigeria (AP) – Nigeria has been rocked by two mass abductions from schools in the past week, with over 300 children taken by armed gangs in the conflict-battered north.

A tally by The Associated Press shows at least 1,799 students have been seized in a dozen of the largest abductions since the 2014 Chibok attack in which Boko Haram militants seized 276 schoolgirls, sparking global outrage. Most of the children have been released, many after ransoms were paid. Others have escaped.

Here is a timeline of major abductions of students in Nigeria:

Members of the Islamic militant group Boko Haram take 276 female students in a nighttime attack at a government secondary school in Chibok in Borno State. More than 90 of the students are still reportedly missing.

A Boko Haram faction takes 110 schoolgirls from a science college in Danchi in Yobe State. Nearly all were later released, but five of the girls were killed.

Gunmen on motorcycles attack a government secondary school in Kankara in Katsina State and take more than 300 boys. The state government announced their release six days later following negotiations.

Gunmen wearing military fatigues attack a science college in Kagara in Niger State and take 27 students, three staff members and others. They were released over a week later.

Gunmen take over 300 schoolgirls in a nighttime raid on a government secondary school in Jangebe in Zamfara State. All were released within weeks after the apparent payment of ransom.

Gunmen take 39 students from the Federal College of Forestry Mechanization in Afaka in Kaduna State. They are released in the following weeks.

Armed men attack the private Greenfield University in Kaduna State and take at least 20 students. Most were released but five were killed, apparently because ransom negotiations were taking too long.

Gunmen take over 100 students from Bethel Baptist High School in the Chikun area of Kaduna State. The students are released over several months.

Gunmen riding motorcycles take 287 students at the government secondary school in Kuriga in Kaduna State.

Armed men break into a boarding school in Gidan Bakuso in Sokoto State and seize 15 children as they sleep.

Gunmen attack a school in Kebbi State and take 25 students while killing at least one staff member.

Armed gangs storm a Catholic school in Niger State and take over 300 students and staff.