Gunmen killed at least 15 people, including a priest, and left dozens more wounded, in an attack on a Catholic church in the Central African Republic (CAR) on Tuesday.

The May 1 attack took place at Our Lady of Fatima parish in the capital Bangui, on the outskirts of the PK5 neighborhood, a largely Muslim area known for violent clashes.

Witnesses told Reuters that gunmen armed with grenades attacked the church during Mass, trapping churchgoers inside. Some were able to escape through a hole in the church wall made by police.

At least 15 were killed, including a priest identified as Fr. Albert Toungoumale Baba, and as many as 99 others were wounded.

After the attack, angry protesters carried the body of Fr. Baba on a stretcher to the presidential palace, according to Reuters witnesses.

A U.N. spokesperson said the attack on Our Lady of Fatima began after a suspected member of a rebel group was arrested in the PK5 neighborhood, according to the BBC.

Last month, 28 people were killed in PK5 in clashes between rebels and U.N. peacekeeping forces.

It is the same parish that was attacked in May 2014, which left at least 17 people dead, including a priest, and 27 others abducted by rebels. At the time, the church had been hosting 9,000 internally displaced persons, who were forced to relocate after the attack.

The Central African Republic has suffered violence since December 2012, when several bands of mainly Muslim rebel groups formed an alliance, taking the name Seleka, and seized power.

In reaction to the Seleka's attacks, some Central Africans formed self-defense groups called anti-balaka. Some of these groups, mainly composed of Christians, began attacking Muslims out of revenge, and the conflict took on a sectarian character.

A general election was held in 2015-16 which installed a new government, but militant groups continue to terrorize local populations. Thousands of people have been killed in the violence, and at least a million have been displaced. At least half of Central Africans depend on humanitarian aid, the U.N. reports.

Bishop Juan José Aguirre Munoz of Bangassou has worked to shelter thousands of Muslim and Christian refugees displaced by the violence.

Pope Francis visited the CAR during his trip to Africa in 2015, and urged the country’s leaders to work for peace and reconciliation.