Nigerian gunmen on Wednesday kidnapped 73 students after storming a high school in the northwest of the country in the latest in a series of mass abductions targeting pupils.
Kidnapping for ransom by armed gangs known locally as bandits has become a grim trend in northwest and central Nigeria, with around 1,000 students snatched this year -- most of them later released.
A large group of gunmen invaded the secondary school in Kaya in the Maradun region of Zamfara State late Wednesday morning, abducting the 73 students, the state police said in a statement.
"The abduction followed the invasion of the school by large numbers of armed bandits," police spokesman Mohammed Shehu said.
He said police rescue teams were working with the military to try to release the students.
Zamfara State officials imposed some night-time road travel restrictions, and primary and secondary schools were temporarily closed, state information commissioner Ibrahim Dosara said.
Northwest and central states have for years been troubled by tit-for-tat attacks and community raids between nomadic herders and local farmers who clash over water and land.
But violence has escalated sharply with the emergence of large criminal gangs who steal cattle, raid and loot villages and kidnap for ransom.
President Muhammadu Buhari, a former soldier first elected in 2015, is under pressure over insecurity and the armed forces have launched military raids and air strikes on bandit camps, but gunmen have kept up attacks and abductions.
Four states across the northwest, including Zamfara, have introduced restrictions aimed at curtailing bandit activities, including limiting motorbike traffic, restricting some fuel sales and also suspending cattle markets and transport.
Armed gangs often arrive on motorbikes during their abduction attacks and also engage in castle rustling.
They operate out of camps hidden in forests in northwest Nigeria, often raiding and abducting in one state and crossing back with their victims into another state.
This year bandits have turned their sights on schools, seminaries and colleges across the region, herding children and students deep into forest hideouts while they negotiate ransom payments.
Many students have been released only after spending weeks or months in captivity. Dozens are still being held.
Zamfara saw 18 students freed last week after they were kidnapped earlier in August from an agricultural college.
Gunmen last week also freed nearly 100 children taken from an Islamic seminary in May in northwest Niger State and 32 students taken from a Baptist school in Kaduna State in July.
The bandits are seeking financial gain and have no known ideological leanings, but there are growing worries among security experts and officials over their ties with jihadists fighting a 12-year war in Nigeria's northeast.