A government spokesman has said Abuja residents should remain calm tonight, saying that security agencies are now "handling the situation."
The latest explosion in Nigeria's capital, Abuja, killed 21 and injured 17 people in a shopping complex.
Spokesman Mike Omeri told AP: "Every step is being taken by the government to check the activities of insurgents in the country."
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His mother Princess Diana was killed in a car crash in Paris in 1997 when he was just 12 and his brother William was 15.
The 21-year-old, who was arrested on Sunday, also allegedly injured two other people in the attack in the German city of Reutlingen.
She was going to the aid of a family member who got out of the car in the middle of the park and was dragged away by a different tiger.