( CNN ) Either one or two suicide bombers struck outside a stadium Monday in Gombe , Nigeria , after President Goodluck Jonathan ended a campaign rally at the site and had left , officials said . Police said one female bomber detonated explosives , killing herself and another person . But rescuers and medical sources said both women were suspected to be suicide bombers . The number of injuries was also unclear . Fwaje Atajiri of the Gombe Police Command said six people had minor injuries . Rescuers and medical sources reported 18 people injured in a blast were being treated at a hospital . The bomber was `` a long distance '' from where the rally had taken place , due to security measures , Atajiri said . Jonathan had left an hour earlier and was already out of the city when the blast occurred , he added . There was no immediate claim of responsibility for the blast . Gombe , in northeastern Nigeria , is one of the sites that has faced repeated attacks blamed on the militant Islamic group Boko Haram .
There were either one or two female suicide bombers , authorities said . The attack was the deadliest in France since a series of coordinated attacks killed 130 people at Paris cafes and bars on Nov. 13 last year.