"There was a blast at Malkohi IDP (internally displaced persons) camp in Yola around 11 o'clock this morning (1000 GMT)," Red Cross official Aliyu Maikano said.
There were conflicting reports of the death toll at the camp, one of several in the capital of Adamawa state housing men, women and children who have fled the brutal, six-year conflict.
Adamawa state police spokesman Othman Abubakar told AFP two people were killed and seven injured, while the Red Cross' Maikano put the toll at three dead and nine injured.
The Adamawa state governor, Jibrilla Bindow, was reported as telling a meeting of northern governors that children were among the dead.
"There were NEMA (National Emergency Management Agency) officials, IDPs and some from the AUN (American University of Nigeria)" among the casualties, said Mohammed.
Lionel Rawlings, head of security at the AUN, which is based in Yola, confirmed student volunteers were injured by flying debris.
"None was in direct contact with the explosion but there was flying shrapnel. We dodged the bullet," he said.
Security had been tight after hundreds of women and children held hostage by Boko Haram were brought to the camp after they were rescued by the military earlier this year.
Armed soldiers manned the gates and carried out checks on vehicles and passengers, AFP reporters witnessed on a visit to the camp in May.
"Our men are there," said Abubakar. "They are trying to find if there are any other explosives.
