A car bomb went off near a stadium in the northeastern Nigerian city of Gombe on Monday, a few minutes after President Goodluck Jonathan left a party rally there, killing one person and wounding 18.
A Reuters photographer said the bomb exploded about 200 metres (220 yards) from the stadium, engulfing the car in flames, while residents fled in panic.
A hospital source said one body had been brought in and 18 people were being treated for wounds, some of them serious.
There was no immediate claim of responsibility, although suspicion is likely to fall on Islamist militant group Boko Haram, which has attacked Gombe several times. On Sunday a suicide bombing near a mosque in the market area there killed five people and wounded eight.