Four people were killed Sunday at a Catholic church in northern Burkina Faso in the latest in a series of attacks on Christian targets in the region, according to a bishop in the region and a security source.

"The Christian community of Toulfe was the target of a terrorist attack which gathered for Sunday prayers. The attack left four of the faithful dead," the Bishop of Ouahigouya, Justin Kientega, said in a statement.

Earlier a security source has said three people were killed in the attack.

"Heavily armed individuals attacked the church... as the faithful were celebrating Sunday mass" in the town of Toulfe, the source said, adding that three people were killed.

Last week gunmen killed four Catholics in a religious procession, the day after a priest and five parishioners were murdered at mass.

Also last week, French special forces freed four foreign hostages in the former French colony during an overnight raid that cost the lives of two soldiers.

Burkina Faso's population is around two-thirds Muslim and one-third Christian.

The semi-desert country has suffered from increasingly frequent and deadly attacks attributed to a number of terrorist groups, including Daesh terror group's Greater Sahara branch.

The raids began in 2015 in the north before targeting the capital Ouagadougou and other regions, notably in the east.

Nearly 400 people have been killed since 2015 -- mainly in hit-and-run raids -- according to an AFP tally.

Terrorist groups have targeted both Christian and Muslim clerics in a country where traditionally both religions have co-existed peaceably.

France has deployed 4,500 troops in Mali, Burkina Faso, Niger and Chad in a mission codenamed Barkhane to help local forces flush out terrorists.