More than 90 Nigerian schoolgirls are reportedly missing after the Boko Haram extremist group attacked their school two days ago in the northeastern state of Yobe.

People with direct knowledge of the matter said 91 students were found to be absent after a Tuesday roll-call at the school.

The disappearance has raised fears of another mass kidnapping by Boko Haram, which abducted 276 girls from a school in the village of Chibok in April 2014.

That abduction sparked worldwide outrage and triggered formation of the Bring Back Our Girls movement. Nearly four years later, more than 100 of the Chibok girls are still missing.

FILE - Remaining girls who were kidnapped from the FILE - Remaining girls who were kidnapped from the northeast Nigerian town of Chibok are seen in an unknown location in Nigeria in this still image taken from an undated video obtained on Jan. 15, 2018. FILE - Remaining girls who were kidnapped from the northeast Nigerian town of Chibok are seen in an unknown location in Nigeria in this still image taken from an undated video obtained on Jan. 15, 2018.

Fearing a repeat of the Chibok abductions, dozens of parents and guardians gathered Wednesday at the Government Girls Science Secondary School in the town of Dapchi demanding information.

Map showing Dapchi and Chibock, Nigeria

"Our girls have been missing for two days and we don't know their whereabouts," said Abubakar Sheu, an uncle of one of the missing students.

"I saw girls crying and wailing in three Tata vehicles and they were crying for help," said a witness from the village of Gumsa who was reportedly forced to direct the insurgents out of the area.

Official denial

Nigerian police and the regional Education Ministry have denied abductions occurred, despite parental and other witness accounts that the girls are missing. The state ministry of education also denied the abductions, but closed the school for a week to allow students and their families to reunite.

Witnesses told Reuters Boko Haram militants arrived in Dapchi Monday evening in trucks, some armed with heavy guns. They said the insurgents immediately went to the school firing guns sporadically. Nigerian security forces, they said, launched a search and rescue mission shortly thereafter.

Since Boko Haram began its insurgency in 2009, more than 20,000 people have been killed and 2 million others forced to leave their homes in northeastern Nigeria, Africa's most populous country.

The group has used kidnapping as a weapon of war, abducting thousands of women and young girls, in addition to boys and men of fighting age.