A suicide bombing at a government compound in the northeastern Nigerian city of Maiduguri killed at least five people and wounded 19 on Thursday, residents and hospital workers said.
A Reuters reporter saw rescue workers loading five bodies on a truck outside the compound, which is home to several government offices. The bombing happened at its gate.
The attack in the city centre looked like the handiwork of Islamist militant group Boko Haram, which has been waging an insurgency in the north for seven years, killing thousands of people and displacing 2.1 million.
Boko Haram has staged suicide bombings inside Maiduguri, capital of Borno state and the heartland of their insurgency to set up a fundamentalist Islamic state.
There had been no attacks in recent months inside the heavily-guarded city centre where the army has set up sand-bagged checkpoints.
Maiduguri has swelled to double its pre-insurgency size over the last few years to around 4 million people as it has become the refuge for most of the displaced population.
The army under President Muhammadu Buhari has recaptured much of the territory it had lost to Boko Haram under his predecessor Goodluck Jonathan, but militants keep staging suicide bombings against markets and places of worship.