Nigeria's Maiduguri shaken by 'Boko Haram' blasts
The loud explosions that have rocked Nigeria's northern city of Maiduguri were orchestrated by the militant group Boko Haram, an army spokesman has said.
Lt Col Sagir Musa told the BBC the multiple attacks targeted locations used by the Joint Military Taskforce (JTF) in the city, the Islamists' base.
He said 24 militants had been killed but denied reports that civilians or soldiers had died.
Witnesses say a primary school and a radio tower were set ablaze.
Last month the group, which wants to impose Sharia across Nigeria, attacked mobile phone masts across the north of the country - accusing mobile phone companies of helping security agencies to monitor its members.
Earlier in October witnesses said soldiers shot dead up to 30 civilians after a bomb attack on an army patrol in Maiduguri - accusations the army denied.'Lockdown'
Lt Col Musa said the explosions were caused by rocket-propelled grenades and improvised explosive devices.
"This is not the first time that Boko Haram [has] used rocket-propelled grenades," he told the BBC's Focus on Africa programme.
"The JTF recovered many assorted arms and ammunition," he said.
City residents say the latest trouble began on Monday afternoon when gunmen robbed a market.
There are also reports that a gunman shot dead a traffic warden in the city close to a military checkpoint.
Explosions were then heard, starting at around 18:00 local time (17:00 GMT) - some residents say there were up to 15 blasts, the last one the loudest which shook the city.
Reports said soldiers sealed off nearly every street in the city centre when the attacks began and continued after dark.
Some residents were unable to get home overnight.
The BBC's Abdullahi Kaura in northern Nigeria says journalists face difficulties confirming casualties when covering such attacks as the authorities always try to downplay the situation.
In the incident earlier this month, soldiers in Maiduguri reportedly opened fire on a busy street after a bomb attack killed an army officer.
Shops and homes were also torched, witnesses said.
The army denied killing civilians although correspondents say it offered contradictory explanations about what had happened.
Attacks in central and northern Nigeria blamed on Boko Haram have killed some 1,400 people since 2010.