Prosecutors brought conspiracy and assault charges against the suspects, though Nigeria has strict new anti-terrorism laws that make the death sentence mandatory for anyone found guilty in an attack that causes fatalities.
The fate of four other men accused in the same trial was not immediately known.
The eight are believed to belong to the Boko Haram Islamic sect that is terrorizing northeast Nigeria with attacks on schools. Britain yesterday banned Boko Haram - whose name means Western religion is forbidden - making membership of or support of the group a criminal offense.
They had also been accused of shooting dead three police officers on May 23, 2012 and bombing a political rally that killed three people March 3 that year, though it was not clear today if they were convicted in these incidents.
Boko Haram has increasingly targeted civilians in attacks this year that have not been halted by a massive deployment of troops under a state of emergency declared May 14 in the northeastern states of Adamawa, Borno and Yobe.