More than 100 people were killed in coordinated bombings by Islamic extremists in northeastern Nigeria on Sunday, said members of a civilian defense group.

About 80 people died in four blasts in Maiduguri, the capital of the northeastern Borno state, the civilian defense members said.

Twenty-eight bodies were brought to the morgue Monday night from a suicide attack at Monguno market, 134 kilometers (83 miles) from Maiduguri, an official from Maryam Tijjani General Hospital in Maiduguri said on Tuesday. The officials insisted on anonymity for fear of government reprisals.

No group has claimed responsibility for the attacks but they are believed to be by the Islamic extremist group Boko Haram, which frequently uses bombings in its 6-year-old insurgency blamed for the deaths of 20,000 people.

Police however insist the number people killed in the Maiduguri and Moguno attacks is 70. The difference in the figures could be because many of the dead were not taken to the morgue but were buried by their relatives immediately according to Islamic customs, said the civil defense group members.

Police spokesman Victor Isuku said 97 people were wounded in Sunday's attack.

Sunday's attack is the worst since President Muhammadu Buhari was sworn into power in May when he pledged to wipe out the militants in 18 months. More than 1,000 people have died in Boko Haram attacks since Buhari was elected March.