Hundreds of militants have staged a multi-pronged attack on the northern Nigerian city of Maiduguri, witnesses say.
On entering the city, the attackers split into smaller groups – heading for the barracks, the university and an area where civil servants live.
“They set many houses on fire and killed innocent people,” one resident told a local newspaper.
Militants suspected to be from Boko Haram have killed 500 people this year.
Local residents say there was a heavy exchange of fire near Giwa barracks, as the military tried to fight off the insurgents.
Air force jets were seen flying over the city following the dawn attack.
“There is thick smoke billowing. The assailants are hurling explosives into Giwa barracks and the multitude of soldiers inside the barracks are firing back,” local resident Hamisu Musa told the Daily Trust newspaper.
Suspected Boko Haram fighters detained by the military are often held at Giwa barracks – human rights groups say hundreds have died there and torture there has been rife.
The army has denied mistreating suspects.
There was also at least one explosion at Maiduguri university and houses were hit, residents say. It is not clear whether the blasts were set off by Boko Haram or whether they were the result of strikes by the air force.
BBC Nigeria correspondent Will Ross says Boko Haram militants usually attack at night so this was a particularly brazen assault.
Attacks have intensified in recent weeks despite a state of emergency being declared in north-eastern Nigeria last year.
Boko Haram was founded in Maiduguri in 2009. It wants northern Nigeria to become an Islamic state.