At least 21 people were killed when a suspected bomb tore through a crowded shopping district in the Nigerian capital Abuja during rush hour.
It was not immediately clear who was responsible for the blast and no one claimed responsibility.
However, militant Islamist group Boko Haram has increasingly targeted civilians in its bloody five-year insurgency.
The suspected bomb would be Abuja's third in three months and comes as the Nigerian government and military face rising public anger over their inability to protect citizens from daily gun and bomb attacks across Africa's most populous country.
The explosion hit a crowded district near the popular Banex Plaza shopping centre in the upscale Wuse 2 neighbourhood.
Witnesses said the blast shattered windows, sent smoke billowing into the air and carved out a large crater.
Meanwhile, the United Nations Security Council has sanctioned Boko Haram Abubakar Shekau and a splinter group – Ansaru – banning them from international travel and freezing assets under the UN al-Qaeda sanctions list.
Russia had placed a "technical hold" on the designations two weeks ago because it needed more time to review the listings, but diplomats said they lifted the hold today, allowing the sanctions to come into force.
Last month, the Security Council al-Qaeda sanctions committee blacklisted Boko Haram at the request of Nigeria, following global outrage when the group kidnapped more than 250 girls from a school in remote northeastern Nigeria on 14 April.
The Islamist militant group was described in the UN listing as an affiliate of al-Qaeda and the Organisation of al-Qaeda in the Islamic Maghreb (AQIM).
It is subjected to a travel ban, an asset freeze and an arms embargo.
Boko Haram faction Ansaru, blamed for the killing of several Western hostages, is AQIM's bona fide affiliate in Nigeria, and called itself "al-Qaeda in the Land Beyond the Sahara" in a video with a British and Italian hostage in 2011.
Ansaru broke off from Boko Haram in protest at its killing 186 mostly Muslim civilians in the medieval Islamic city of Kano in early 2012.
Shekau is the purported leader of Boko Haram. A year ago, US Secretary of State John Kerry authorized a reward of up to $7 million for information leading to his location.