YOLA, Nigeria (AP) — A Nigerian official says three people have been killed in an explosion at a camp for people displaced by attacks of Islamic extremists.

Saad Bello, the National Emergency Management Agency coordinator for Adamawa state, said nine people were also wounded by the explosion Friday in a tent in the Malkohi camp in Yola, capital of the northeastern state.

No group has claimed responsibility for the blast, but suspicion has fallen on Islamic extremist group Boko Haram.

Boko Haram's uprising, which started in 2009, has caused the deaths of an estimated 20,000 people.

More than 1,000 people have been killed since President Muhammadu Buhari was elected in March with a pledge to wipe out the militants. At least 2.1 million have been driven from their homes by the uprising.