Witnesses say a powerful explosion has shaken a city in northeast Nigeria that's the spiritual home of a radical Islamist sect.

The blast Monday morning struck Maiduguri at a military post near the local headquarters of the Nigeria Union of Journalists. Authorities immediately suspected the sect known as Boko Haram, though the group did not immediately claim responsibility. A military spokesman later said only two soldiers were wounded in the attack, though the military routinely downplays their losses.

On Sunday, officials say a Chinese worker near Maiduguri was shot and killed while in a local market. Meanwhile, the military claimed to kill 30 Boko Haram fighters, though that information could not be independently verified.

Boko Haram is waging a bloody guerrilla fight against Nigeria's weak central government.