Explosion at north Nigeria Catholic church

Witnesses say an explosion has struck near a Catholic church in north Nigeria, a region under attack by a radical Islamist sect.

An Associated Press journalist heard the explosion after 9 a.m. Sunday in the city of Bauchi. The AP journalist said the blast occurred at St. John's Catholic Church in the city.

Emergency responders declined to immediately say whether there were casualties, though the explosion occurred during an early morning Mass.

A radical Islamist sect known as Boko Haram has attacked churches throughout Nigeria's north with gunmen and suicide car bombers. The sect is blamed for more than 680 killings this year alone in Nigeria, according to an AP count.