( CNN ) -- Bomb blasts Monday in Nigeria 's northeastern state of Borno killed three people and wounded dozens , raising fears that an Islamist group will step up attacks against voters on the eve of national governorship elections , police said . In one of three blasts , a bomb thrown from a motorcycle on which two young men were riding detonated , resulting in the three fatalities , said Michael Zukoma , police commissioner for Borno state . Nigerian police told CNN that Boko Haram , an Islamist sect that has challenged Nigeria 's government , is responsible for the attacks , which they described as an attempt to intimidate voters who this month re-elected President Goodluck Jonathan , an ljaw Christian from the south . The explosions occurred a day after the Nigerian Red Cross reported that rural villages had held mass burials in northern Nigeria . Witnesses say that violence in the wake of Jonathan 's election has resulted in hundreds of deaths , though there is no official death toll . The government has provided few details . This month 's election of Jonathan , who is from the majority-Christian southern part of the country , sparked violence in the Muslim-dominated north last week . Concerns about ongoing violence led Nigerian election officials last week to delay the planned gubernatorial elections in two of Nigeria 's 36 states . Northern Muslims in some areas charged that the presidential election was rigged . Armed protesters in the region took to the streets chanting the name of former military ruler Muhammadu Buhari , the main opposition front-runner . The last election , four years ago , was widely condemned for rampant vote rigging , violence , theft of ballot boxes and intimidation . While this month 's presidential election was marred by violence , reports of underage voting and logistical problems , observers said they considered it an improvement . After he was declared the victor , Jonathan warned that persistent post-election violence could threaten the stability of the country . `` These acts of mayhem are sad reminders of the events which plunged our country into 30 months of an unfortunate civil war , '' Jonathan said last week . Jonathan was referring to a period of unrest in the 1960s that spawned a civil war in Nigeria . Nigeria is Africa 's largest oil producer and its most populous nation , with 150 million people .
NEW : All three fatalities were from a single bomb blast . Presidential elections scheduled for Tuesday . Police blamed Boko Mali , an Islamist group , for the attacks .