An explosion ripped through a Catholic church during Christmas Mass near Nigeria's capital Sunday, causing unknown injuries amid a wave of sectarian attacks targeting Africa's most populous nation.

Local police spokesman Richard Oguche said the blast struck St. Theresa Church in Madalla, a town in Niger state close to the capital, Abuja. Oguche said he had no other details and was driving to the scene of the explosion.

It was not immediately known what had caused the explosion or how many people were injured. Nigeria's National Emergency Management Agency, however, sent a text message to journalists warning it did not immediately have enough ambulances to begin ferrying the wounded to hospital.

The explosion comes amid a wave of attacks in Nigeria by a radical Muslim sect known as Boko Haram. In the last year, the sect has carried out increasingly bloody attacks in its campaign to implement strict Shariah law across Nigeria, a nation of more than 160 million people with a largely Christian south and a Muslim north.

Previously, Boko Haram has been blamed for other bombings in Niger state, including attacks on an election office, a political rally and a church.

The sect is responsible for at least 465 killings this year alone, according to an Associated Press count.