Nigeria's military has declared a 24-hour curfew on a dozen neighbourhoods in a northeastern city that is a stronghold of the armed group Boko Haram.
The move in Maiduguri, the main city in Borno state, came as soldiers continued the government's emergency campaign against fighters in the region on Saturday.
The military deployed jets and helicopters to carry out air strikes on fighter camps, and said 10 fighters had been killed and another 65 arrested.
A spokesman for Defence Headquarters also said the military had seized stockpiles of weapons including rocket-propelled grenades, guns and ammunition from areas around Maiduguri, the main city in the northeast.
Boko Haram, which has said it is fighting to create an Islamic state in Nigeria's mainly Muslim north, has carried out scores of attacks in recent years, and has become emboldened and better armed in recent months.
Nigeria launched a massive offensive against the group this week, deploying several thousand troops across three states where President Goodluck Jonathan declared a state of emergency after the fighters seized territory and chased out the government.
Nigeria's offensive is targeting all three states put under emergency decree, including Adamawa and Yobe, but Boko Haram's traditional base of Borno, where is expected to see the most intense fighting.
In Marte district of Borno state, some residents have started fleeing east towards the Cameroon border, less than 25km away.
"It has been scary in the past three days," said Buba Yawuri, whose home is in the town of Kwalaram in Marte but who has fled to the border town Gomboru Ngala.
"Fighter jets and helicopters kept hovering in the sky and we kept hearing huge explosions from afar."
Yawuri 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 Saturday, he said.
Shafi'u Breima, a resident of Gomboru Ngala, said the border town is receiving a continuous flow of people arriving from Marte and neighbouring areas.
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.
"Border posts have all been manned by security agents to prevent escape or infiltrations by insurgents," a military statement said.
The latest military campaign could prove to be the biggest ever 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.
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."
Boko Haram has said it is fighting to create an Islamic state but the group's demands have repeatedly shifted. The conflict is estimated to have cost 3,600 lives since 2009, including killings by the security forces.