What does the news item mainly report?

(6)At least ten people have been killed in an upsurge of violence in Nigeria on the eve of Saturday’s parliamentary elections. A bomb at electoral commission offices in the central town of Suleja left at least five dead.
    Reports from the town of Suleja suggest that the explosion happened at around six o’clock in the evening. A senior figure in the election commission told the BBC that the officers were busy at the time. Official paperwork had been delivered and staff were still at work as the explosion ripped through the building.(7)He added that he was making frantic efforts to contact election workers. Some are still unaccounted for. In the northeastern state of Borno, gunmen shot dead four people at a police station where election officials were preparing voting materials. Earlier, a man died in the northern city of Kaduna when a bomb he was carrying exploded.