An Associated Press journalist heard the blasts Monday afternoon. Police and military officials did not answer repeated calls for comment as sirens wailed. Some witnesses said at least one blast targeted a primary school, which was in flames. Soldiers blocked off streets.
Earlier, witnesses say a gunmen shot dead a police traffic warden in the city in view of a military checkpoint, then walked away unstopped.
The explosions come during a renewed offensive by the Boko Haram sect. The sect has been fighting with Nigeria's weak central government for months to get its members released and enact strict Shariah law across the nation.
(Copyright 2012 The Associated Press. All rights reserved.)