Kano, Nigeria: Nigeria’s military on Saturday imposed a 24-hour curfew in parts of a northeastern city as soldiers pressed on with a campaign against Boko Haram Islamists that has sent people fleeing from their homes.

Nigeria launched the sweeping operation this week, deploying thousands of troops across three states where President Goodluck Jonathan declared a state of emergency after the Islamists seized territory and chased out the government.

The group, which has said it wants to create an Islamic state in Nigeria’s mainly Muslim north, has carried out scores of attacks since 2010, and has become emboldened and better armed in recent months.

In the city of Maiduguri, the Borno state capital and Boko Haram’s traditional home base, a “24-hour curfew” was imposed in 12 neighbourhoods, military spokesman Lieutenant Colonel Sagir Mousa said in a statement.

In a separate release, the military claimed the killing of “10 suspected terrorists” in one Maiduguri neighbourhood and arrested 65 others who were trying to enter the city after fleeing aerial bombardments elsewhere.

The military said dozens of insurgents had been killed in the offensive targeting all three states put under emergency decree, including Adamawa and Yobe, but Borno is expected to see the most bloodshed.

Residents have begun escaping from a remote insurgent stronghold in Borno near the border with Cameroon after military fighter jets and helicopters carried out air strikes on Islamist camps.

In the Marte district, some people were fleeing east towards a town on the border about 40 kilometres away, called Gomboru Ngala.

“It has been scary in the past three days,” said Buba Yawuri, whose home is in the town of Kwalaram in Marte but is now in Gomboru Ngala.

“Fighter jets and helicopters kept hovering in the sky and we kept hearing huge explosions from afar,” he told AFP.

He said that as the air assaults began, the security forces told all residents to stay indoors, cutting off his family’s access to food and water.

“I couldn’t hold on any longer. I took the bush path” and reached Gomboru Ngala early on Saturday, he said.

A teacher who arrived in Gomboru Ngala on Saturday said he fled his village in Marte because he feared how the Islamist fighters might respond to the air strikes.

“I don’t want them to vent their anger on me,” Babakura Kachalla told AFP.

“I am a known school teacher and I know how much Boko Haram hates people like me,” a reference to the Islamist group’s name, which means “Western education is a sin”.

The phone network in Borno state has all but collapsed since the emergency measures were imposed but residents in Gomboru Ngala use phone services from Cameroon and have been sporadically reachable.

The remote, thinly populated region has porous borders where criminal groups and weapons have flowed freely for years.

The military has sealed previously unguarded crossings to block Boko Haram fighters from fleeing during the offensive.

The military campaign could prove to be the biggest yet against Boko Haram and is believed to be the first time Nigeria has carried out air strikes within its own territory in more than 25 years.

Aerial support was believed to have been used against rioters in the north in the early 1980s.

Many have warned that there is a risk of high civilian deaths and Nigeria’s military has been accused of massive rights violations in the past, including indiscriminate attacks on civilians.

US Secretary of State John Kerry said on Friday that he was “deeply concerned about the fighting in northeastern Nigeria” and urged the security forces to “apply disciplined use of force in all operations”.

There are also doubts as to whether the insurgency can be crushed by force, amid concern that the militants will scatter and re-emerge when the offensive eases.

“I don’t think that only using the stick can crush the movement. But, the stick combined with the carrot, that could achieve something,” said Marc-Antoine Perouse de Montclos, a Nigeria expert at the Institute for the Research of Development in Paris.

Nigeria has been urged by various camps to tackle the root causes of the conflict, including acute poverty and excessive government corruption which has helped radicalise many young Muslims in the north.

The conflict is estimated to have cost 3,600 lives since 2009, including killings by the security forces.