Humanitarian organisations and media remain restricted in areas where fighting takes place against Boko Haram.
A blast at a bus depot on the outskirts of the Nigerian capital Abuja has killed dozens of people during the morning rush hour.
The blast, around 7am at the Nyanya Motor Park, destroyed more than 30 vehicles and caused secondary explosions as their fuel tanks exploded and burned.
Reporters saw rescue workers and police gathering body parts.
“We have been able to bring some of the dead to the morgue and some injured have been taken to the hospital,” said Charles Otegbade, head of search and rescue at the National Emergency Management Agency (NEMA).
He said his team had not yet been able to provide precise figures on casualties.
A Reuters camerman reported seeing 20 bodies at the depot at Nyanyan bridge, around 8km south of Abuja, and two witnesses said another 15 had already been removed by the emergency services.
“I was waiting to get on a bus when I heard a deafening explosion then smoke. People were running around in panic,” said Mimi Daniels, who works in Abuja. Another blast followed, she said, according to Reuters news agency.
There was no immediate claim of responsibility but suspicion is likely to fall on armed group Boko Haram. The group has been involved in increasing levels of violence in the northeast.
Suspected Boko Haram members killed at least 60 people in an attack on a village in northeast Nigeria late last week. Eight people were killed in a separate attack at a teacher training college, witnesses said.