Shots were fired into a crowd of about 1,000 Friday worshipers at the Gomari Jumat mosque in Maiduguri by two men who came on a motorbike wielding assault rifles.
"Two suspects and 11 others have been arrested in relation to the attack and other killings in the area," Borno State Police spokesman Lawan Abdullahi said.
According to Abdullahi, the attackers are suspected to be members of Boko Haram sect, which denounces Western education as sacrilegious and may have been culpable for killing several policemen and local politicians recently.
Last week, gunmen killed a soldier and wounded another at a restaurant in similar manner. Violence by members of the group led to the death of over 800 people last year.
Leader of the group - Muhammed Yusuf - was captured and killed by the Nigerian military on July 30, 2009. The sect wants to enforce Islamic law across Nigeria and in the process has burnt churches, attacked police stations and a prison and clashed with security forces in the northern states of Bauchi, Borno, Kano and Yobe.
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