LONDON and MAIDUGURI, Nigeria -- Hundreds of students remain missing after gunmen attacked an all-boys boarding school in northwestern Nigeria, authorities said.
A group of "bandits" wielding assault rifles stormed the Government Science Secondary School in the town of Kankara in Katsina state on Friday night, according to a statement from Katsina State Police Command spokesperson Gambo Isah.
Police officers engaged the assailants in a gunfight that gave some of the students "the opportunity to scale the fence of the school and run for safety," Isah said in the statement Saturday. More than 200 pupils have since been located, but around 400 others are unaccounted for, according to Isah.
However, after meeting with security officials on Sunday, Katsina state Gov. Aminu Bello Masari said a total of 839 students are enrolled at the Government Science Secondary School and that the number of those still missing is 333. It's unclear how many were abducted and how many others fled during the attack and have yet to be found.
No group or individual has claimed responsibility for the attack or kidnappings so far, according to Masari.
Nigerian President Muhammadu Buhari has condemned the attack and urged school officials to carry out an audit of the student population to ascertain the exact number of those missing and those who have been found.
"Our prayers are with the families of the students, the school authorities and the injured," Buhari said in a statement Saturday.
The Nigerian military located the attackers' enclave in the nearby Zango-Paula Forest, and there was an exchange of gunfire during an ongoing police operation, according to a statement from Buhari's spokesman, Garba Shehu. No student casualties have been reported, Shehu said.
It's unclear whether any students have been rescued yet.
Col. Sagir Musa, spokesperson for the Nigerian Army, did not respond to ABC News' questions about whether the military will seek the help of U.S. troops for the rescue operation.
Parents have gathered at the Government Science Secondary School in recent days, pleading with officials to find their children and expressing anger over the changing numbers.
Malam Nasiru Ahmed, whose son is among the students still missing, said one fear is that if authorities fail to rescue the abducted the children, the attackers will kill them or turn them into child soldiers.
"Our fears grow each passing day," Ahmed recently told reporters.
It's the latest attack on a school to occur in the West African nation. One of the most well-known attacks happened in April 2014, when members of the militant group Boko Haram kidnapped 276 girls from their dormitory at a boarding school in Chibok, a town in northeastern Nigeria's Borno state. Some of the girls managed to escape on their own, while others were later rescued or freed following negotiations. But the fate of dozens remains unknown.