Updated

Nigerian military officials say they killed about 70 Boko Haram fighters when the Islamic extremists attacked the northeastern town of Bama Monday morning.

The militants arrived Monday morning in armored tanks and trucks and tried to take over the town, said the officials, who insisted on anonymity because they were not authorized to speak to the press.

"#Bama attack is being repelled," tweeted Nigeria's Defense Headquarters in Abuja. "We cannot state casualty situation/figures now. Everything necessary will be done to contain the Terrorists."

Most of Bama's residents fled to Maiduguri, said Muhammed Gava, a spokesman for the anti-Boko Haram vigilante movement.

"There was an attempt by the Boko Haram people to enter and capture Bama as they did in Gwoza some weeks back, but thank God for the  efforts of the soldiers stationed near the mobile police unit who were able to repel them," said Mohammed Bunu Ahmed, a witness.

Sani Usman, an army spokesman, said Monday the curfew in Maiduguri has been extended from 7 p.m. to 6 a.m.

Amnesty International said last month that more than 4,000 people -- mostly civilians -- have been killed this year in the Nigerian conflict, including in Boko Haram attacks and in responses by the security forces.

Boko Haram has been fighting in Nigeria since 2009 but became internationally known in mid-April when its militants kidnapped more than 300 schoolgirls, of whom more than 200 still remain captive.