As attackers opened fire on worshippers inside a Catholic church in southwestern Nigeria, other gunmen waited outside to kill those who tried to flee; church officials and witnesses said Monday.

At least 50 people including children were killed in the attack, according to a state lawmaker from the area. No one has claimed responsibility for the massacre, and local authorities said the gunmen have since absconded.

While northern Nigeria has battled an Islamic insurgency for more than 13 years, Ondo state has long been considered one of the most peaceful states in the country.

According to africanews, worshippers were attending Pentecost Sunday Mass when gunfire erupted at the St. Francis Catholic Church in Ondo state.

Bishop Jude Arogundade of the Ondo Diocese said there were gunmen inside the church but also other gunmen outside who then killed churchgoers fleeing in terror.