Tragedy struck a Roman Catholic church in Nigeria on Sunday, when one gunman — or two, reports differ — opened fire during a mass, killing at least 11 people and leaving at least 18 critically wounded.

“The holy Mass had proceeded as usual, after the first, second, and gospel reading, and then the priest’s homily, as we stood up for the proclamation of faith, there was a sound of gun, like thunder from behind,” lay reader Ogochukwu Maduka told Premium Times Nigeria. “There was chaos and panic and confusion. The priest ran away as the gunshots continued and I took cover under the seat.”

The shooting took place during the 6 a.m. Mass at Saint Philips Catholic Church in Ozubulu, a city in the southern Nigeria state of Anambra, which has a 98 percent Igbo population.

Charles Justice, a parishioner who brought his wounded friends to the Nnamdi Azikiwe Teaching Hospital, told Premium Times that it was mostly the very young and very old who died. “Those who died are mostly children and the elderly, I know about three children who were below five years that died in the shooting,” Justice said.

The state’s police commissioner, Garba Umar, told the Times that this was “definitely not a terrorist attack in the mould of Boko Haram of Fulani herdsmen attack.” The terrorist group Boko Haram has links to the Islamic State (ISIS) and is believed to be responsible for more than 20,000 deaths. But Boko Haram is mostly in the northern part of the country, far from this church.

Instead of terror, the police investigation pointed to a feud between two individuals on the same community — “one of the individuals built the church where the shooting occurred.”

Many details of the attack remain unclear. Police Commissioner Umar suggested it was one gunman in the attack, but parishioner Uche Nonoso told the Associated Press that there were two gunmen. Many reports have said there were at least 11 dead, but Nonoso put the death toll at 15, as did lay reader Ogochukwu Maduka. Some sources suggested much higher casualty counts, from 47 dead to over 50.

Assistant Police Commissioner Abayomi Shogunle shared a photo from the scene on Twitter, crediting the Nigerian Police Force and insisting that the attack was caused by “DRUG GANG” violence, not terrorism.

The sad #Ozubulu Anambra church shooting incident is DRUG GANG related involving indigenes, NOT TERRORISM. Read at https://t.co/Ua9F9G0y8x pic.twitter.com/36v8ZZBuBT — Abayomi Shogunle (@YomiShogunle) August 6, 2017

Pope Francis released a statement of solidarity after the attack, addressed to the local bishop, Hilary Paul Odili Okeke.

“Deeply saddened to learn of the loss of life and injury following the violent attack in Saint Philip’s Catholic Church, Ozubulu, His Holiness Pope Francis extends heartfelt condolences to you and to all the faithful of the Diocese of Nnewi, in particular the families of the deceased and all those affected by this tragedy,” read a statement signed by the Vatican’s secretary of State, Italian Cardinal Pietro Parolin.

Father Hygi Aghaulor, spokesman of the diocese, asked, “What on earth would make people open fire on innocent unarmed worshipers including children and women on a Sunday morning?

“It is when the forces of darkness attempt to overshadow goodness that the light of God shines even brighter than ever just as it happened on Easter Sunday,” Aghaulor said. “Evil may make attempts but God and goodness will always triumph; we call on the good people to continue to pray for the deceased worshipers and their families.”