Sunday's attack on St Francis Catholic Church in the Nigerian town of Owo left 22 people dead and 50 injured, an official from the National Emergency Management Agency said on Tuesday.
Unknown assailants attacked the congregation with guns and explosives during Pentecost Sunday mass. Authorities had previously not released any casualty figures. Media reports had said more than 50 people were killed.
It is not uncommon for conflicting casualty figures to emerge in the aftermath of disasters in Nigeria.
Authorities have not given any information about the identity of the attackers or their motive.
Police said on Monday they had recovered unexploded bombs as well as casings from bullets used in AK-47 assault rifles.
They said some of the attackers had positioned themselves among the worshippers while others fired into the church from different directions.
Inside the church, streaks of blood on the floors and walls, broken furniture, glass and plaster debris and abandoned personal items testified to the violence of the attack.
Survivors were being treated in hospital for lacerations, bullet wounds and blast injuries, doctors said.
Owo is located in Ondo State in southwestern Nigeria, a part of the country that is not usually prone to religious violence.