Hospitals in southwestern Nigeria say they are running out of supplies to treat survivors of Sunday's attack on a church. Gunmen killed dozens of people as worshippers gathered for Catholic mass in in the town of Owo in Nigeria’s Ondo state. Police say the gunmen who attacked the St Francis Xavier Catholic Church disguised themselves as congregants. The families of the victims say they do not know why a church service was targeted. Africa's most populous country has grappled with severe problems of violence and criminality in the north for more than a decade. But millions may be forced to flee Nigeria if the internal conflict moves south. No group has claimed responsibility for the attack as seven days of national mourning continue. Al Jazeera’s Jillian Wolf reports.