Gunmen who attacked a Catholic church with explosives in southwestern Nigeria killed 21 people, including children.
This statement came according to a preliminary toll released Monday morning by local authorities.
Richard Olatunde, a spokesman for the Ondo State governor's office, told AFP that the gunmen who used dynamite exploded inside the church in the town of Owo before opening fire through the windows during a mass.
This attack which President Muhammadu Buhari described as a "heinous killing of worshippers", which no party has announced yet, also resulted in the injury of many people, according to the authorities.
The attack took place during the morning mass at St. Francis Catholic Church of Owo in Ondo state, which is usually spared from the operations of jihadists and criminal gangs active in other parts of the country.
Local authorities said the security forces were mobilized to find the attackers, whose identities have not been known.
Nigeria is still fighting a 12-year-long jihadist insurgency in its northeast and heavily armed criminal gangs often proceed raids and mass kidnappings in the northwest.
Large attacks in the country's southwest are relatively rare although kidnappings have become increasingly common.