At least eight people have been killed in explosions in Nigeria's capital, Abuja, marring celebrations to mark 50 years since independence from the UK.
Police have confirmed that two blasts outside the justice ministry were caused by car bombs.
Earlier, the militant group Mend (Movement for the Emancipation of the Niger Delta) had threatened to target the festivities.
Nigeria is a major oil producer, yet most of the population live in poverty.
The bombs went off not far from Eagle Square, where the Nigerian elite had gathered for the official celebrations, but no-one there was hurt.
President Goodluck Jonathan, who was inspecting a guard of honour at the time, called it a "wicked act of desperation by criminals and murderers".
'Nothing to celebrate'
Mend, a militant group in the oil-rich south, issued a threat on Friday morning saying it intended to bomb the event.
In the message, the group which is demanding a fairer distribution of the country's oil revenues, said there was "nothing worth celebrating after 50 years of failure".
If Mend militants are responsible for the blasts, it would be the first time that the group has targeted the capital.
At least one of the dead is a police officer.
A fireman at the scene told the BBC that 10 bodies had been found.
The BBC's Ahmed Idris in Abuja says he saw bloody footprints at the scene as emergency workers moved bodies into vehicles.
Our reporter says there may have been a smaller third explosion within the parade ground. Security staff said at the time a gun had gone off accidentally.
The two bombs went off about five minutes apart. Police said the bombs appeared timed to do most damage to those who responded to the first blast.
"There were more casualties at the second explosion because the first explosion drew crowds to the scene, which is close to the second explosion," an intelligence officer told AFP news agency.
"We heard a massive explosion not too far away from us," an eyewitness told the BBC's Focus on Africa programme.
"They said it was a bomb blast and all of us should move... Before we knew it, the second blast just happened. And you can imagine it levelled the people who were very close to that place."
Last year the Nigerian government signed an amnesty agreement with rebels in the Delta, offering cash and the promise of job training for former militants who disarmed.
Violence has lessened and the number of kidnappings has fallen since the deal was reached, but many fighters complain the government has failed to deliver its end of the agreement.
Oil production has increased since the amnesty came into effect - from about 1.6 million barrels per day to about two million now.
Most of Mend's attacks have targeted pipelines and supply terminals in the south.
President Jonathan is himself from the Delta region. When he took office earlier this year, a senior rebel leader told the BBC he would be the best person to solve the crisis in the Delta, as he understands its problems.