Boko Haram islamist militants attacked the northern Nigerian town of Buni Yadi in Yobe state late on Thursday, military sources said, targeting a centre it lost to a Nigerian army offensive in March.
A Reuters correspondent saw a detachment of troops with armoured personnel carriers and a fighter jet heading towards Buni Yadi on Friday morning. It was not clear if fighting was continuing in the area.
There was no information on casualties after the attack, which started at around 9 p.m. (2000 GMT), the sources said on Friday.
"Those boys (Boko Haram) came to Buni Yadi yesterday and attacked our people. They came in about nine Hilux (pick-up trucks) and opened fire ... Our people have mobilised for reinforcement," one of the sources said.
Boko Haram has been trying to carve out a state adhering to strict sharia in the country's northeast since 2009. Buni Yadi was one of the towns that was captured by the insurgent group in 2014 and then reclaimed in March this year by Nigeria's army.
The group took over large swathes of territory last year but were pushed back into their last stronghold in the Sambisa forest reserve with the combined efforts of Nigerian and regional forces, including Niger, Chad and Cameroon.
The militants have since dispersed and reverted to guerrilla tactics, including hitting towns well outside its Borno state heartland such as in Kaduna and Plateau states over the last two weeks.
The U.N. humanitarian coordinator OCHA said at least one civilian was killed and three wounded in an attack by suspected Boko Haram militants on Wednesday on the village of Tchoukoudjani near the shores of Lake Chad in southeastern Niger.
President Muhammadu Buhari has made quashing the insurgency his number one priority and is building up a base in Chad's capital N'Djamena out of which regional forces can deploy and attack the militants.