Gunmen attacked a mosque in the Nigerian town of Konduga with automatic weapons, killing at least 44 people, a local police official said.
The attack happened Sunday morning, but the details have taken time to emerge. The police official in Konduga spoke to CNN on condition of anonymity because he is not authorized to speak to the media.
The mosque is in Konduga town, about 30 kilometers (almost 19 miles) southeast of Maiduguri, the capital of Nigeria's northern Borno state.
The Islamic militant group Boko Haram has carried out attacks in this area before, though police are still investigating this incident.
Local media reports say the leader of Boko Haram, Abubakar Shekau, released a video at the weekend in which he indicated that the militant group is growing in strength.
Nigeria's Daily Trust newspaper quotes him as saying: "By Allah, we have come of age; we now have the capability to face the United States, not to talk of Nigeria."
The U.S. State Department named Shekau as a "specially designated global terrorist" in June last year.
State of emergency
Boko Haram, whose name means "Western education is forbidden," seeks to overthrow the Nigerian government and replace it with a regime based on Islamic law.
A state of emergency has been imposed in Borno state since May 14, including a complete communications blackout, as authorities seek to tackle the militant group.
Yobe and Adamawa states, which border Borno state, were placed under a state of emergency at the same time, according to local media reports.
With an estimated 174.5 million people, Nigeria is Africa's most populous nation. The CIA Factbook says the nation is roughly 50% Muslim and 40% Christian.
Violence between the mainly Muslim north and Christian south has taken at least 2,800 lives, according to Human Rights watch.