Kano: Boko Haram fought running battles with Nigerian troops in a restive northeast city on Friday, as the government vowed to win back territory lost to the militants in recent months.
Dozens of Islamist fighters stormed the Yobe state capital Damaturu at sundown, firing indiscriminately, before they were intercepted by troops, residents said.
"The gunmen arrived around 7:30 pm (1830 GMT), firing guns and shouting `Allahu Akbar!` (God is greatest)," said student Mukhtar Sani.
"All the streets are deserted. Everybody has moved indoors and all we hear are sounds of gunfire," added resident Aishatu Bala.
The clash came nearly a week after Boko Haram fighters captured the strategic town of Baga and overran the headquarters of a multinational regional force in the far north of neighbouring Borno state.
Boko Haram fighters burnt Baga to the ground and razed at least 16 surrounding towns and villages on Wednesday, leading to fears of heavy casualties.
Earlier on Friday, Mike Omeri, who speaks for the government on national security, said a fightback had begun, adding that soldiers were "actively pursuing" the rebels.
"Security forces have responded rapidly and have deployed significant military assets and conducted airstrikes against militant targets," Omeri told reporters in Abuja.
He added: "The government of Nigeria will not rest until Boko Haram is completely dismantled.
"The government values every town, every community and every Nigerian equally. No inch of Nigerian soil will remain in the hands of these terrorists."
The Baga attacks are feared to be among the worst in the insurgency, which began in 2009 and has left more than 13,000 people dead.
But there was no independent corroboration of the potential death toll cited locally.Local government officials said that as many as 20,000 people had been forced to flee their homes while 560 were said to be stranded on an island on Lake Chad since Saturday.
Omeri said Nigeria`s main relief agency was helping 2,000 people displaced from Baga, while other agencies, including the Red Cross, were ready to assist when security allows.
They are among the hundreds of thousands of displaced by the conflict and who have fled within Nigeria and into neighbouring Cameroon, Chad and Niger.
The UN refugee agency said on Friday that 7,300 refugees had arrived in western Chad in the past 10 days after the Baga attack and surrounding villages, taking the number of refugees to more than 10,000.
Boko Haram has for the last six months captured dozens of towns and villages in northeast Nigeria as part of its aim to establish a hardline Islamic state.
The Baga attack effectively gave it control of all three frontiers of Borno state with neighbouring Niger, Chad and Cameroon, increasing fears of cross-border attacks.Security analysts this week said that the militants were now in a better position to strike south towards the Borno state capital, Maiduguri, where the group was founded in 2002.
It has also cast doubt on the ability to hold general elections in the affected areas, scheduled for next month.
Andrew Noakes, co-ordinator of the Nigerian Security Network of analysts, said the assault on Baga may have targeted civilian vigilantes assisting the military after a series of previous strikes.
"Boko Haram had pledged to punish CJTF (Civilian Joint Task Force) members and it looks likely Baga was treated with such brutality to do exactly that, and to send a message to other vigilantes," he said.
Friday evening`s attack in Damaturu was an apparent reprisal for a raid on Tuesday by civilian vigilantes and local hunters on a Boko Haram enclave in Gujba, 40 kilometres (25 miles) to the south.
Several militants were killed and weapons seized, according to a security source in the city.
Boko Haram then killed 25 people and abducted women in Kadarko, 20 kilometres away, before burning the entire village, local vigilantes sources said.