Multiple explosions have killed at least seven people in Nigeria's capital, Abuja, as a ceremony was being held to mark the country's 50th anniversary of independence.
Several others have been injured, and some reports suggested the death toll might be higher.
The blasts came after the country's main militant group, the Movement for the Emancipation of the Niger Delta (MEND), threatened to bomb the ceremony.
Some agencies quoted police as saying an explosion came from a vehicle but could not yet determine whether it was a car bomb or an accident.
Broadcast television footage showed scenes of the event, which was being attended by the country's president, Goodluck Jonathan, continuing.
The MEND has drastically cut Nigeria's oil output through years of sabotage of oil facilities in the southern Niger Delta, saying it was fighting for a more equitable share of resources for indigenous people.
compiled from agency reports