Heavily armed men have kidnapped more than 100 girls from a secondary school in northeast Nigeria's Borno state and torched the surrounding town, a day after a deadly bombing in the African state's capital.
No one claimed responsibility for Tuesday's kidnapping, but fingers were pointed at fighters of the armed group Boko Haram, which means "Western education is forbidden".
The attackers killed a soldier and police officer guarding the school, then took off with at least 100 students, a State Security Service official said.
Some of the girls managed to escape from the back of an open lorry, other officials said.
"Many girls were abducted by the rampaging gunmen who stormed the school in a convoy of vehicles," Emmanuel Sam, an education official in the town of Chibok, where the attack took place, told AFP news agency.
He spoke from Borno's capital Maiduguri where he said he fled after the attack at the Government Girls Secondary School in Chibok.
The attackers came "in trucks and on motorcycles and headed to the school", where they overpowered soldiers deployed to guard it, a witness who requested anonymity said.
The witness said soldiers had been deployed to provide extra security in advance of yearly exams, but the attackers "subdued the soldiers and took the girls away".
A local government official said he did not know how many of the girls had escaped but that "many" have walked through the bushes and back to Chibok.
The girls were piled into the back of an open lorry and, as it was travelling, some grabbed at low-hanging branches to swing off while others jumped off the slow-moving vehicle, he said.
Boko Haram has repeatedly attacked schools in the northeast during an insurgency that has killed thousands since 2009.
In an attack earlier this year in Borno, witnesses said Boko Haram fighters surrounded a girls' school, forced the students to leave and ordered them to immediately return to their villages.
The fighters are known to be abducting girls to use as cooks and sex slaves.
At least 71 people were killed in Abuja's outskirts on Monday, when a bomb exploded at a packed bus station, marking the deadliest attack in the federal capital.
Boko Haram wants to establish a state ruling by Islamic law in the northeast. Nigeria's Muslims mainly live in the north while Christians mostly in the south.
The Abuja explosion raised concerns about the country's ability to ward off frequent attacks during the World Economic Forum on Africa scheduled next month in the capital.
Following the blast, Nigeria has pledged to deploy more than 6,000 police and soldiers to protect African heads of state and business leaders attending the May 7-9 event, based on the flagship gatherings in Davos, Switzerland.
Africa's top oil producer wants to highlight its newly acquired status as the largest economy on the continent.
Monday's attack also added pressure on President Goodluck Jonathan in the run-up to February's elections.