Gunmen burst into a church in northern Burkina Faso on Sunday and shot dead four people, a security source said - at least the fourth attack on Christians in the past month.
Other worshippers were wounded in the assault on the morning service at the church near the town of Titao, the source added.
No one has claimed responsibility for the attacks which threaten to upend traditionally peaceful relations between the Muslim majority and Christians who make up a quarter of Burkinabes.
The government has blamed unnamed terrorist groups operating in the country and Africa's surrounding Sahel region.
Islamist militants based in Mali have regrouped after a French intervention in 2013 and now use the country’s north and centre as launchpads for attacks on neighbouring Burkina Faso and Niger.
Gunmen killed a Protestant pastor and five congregants in another church in northern Burkina in late April. A Catholic priest and five parishioners were killed in an attack in the central town of Dablo on May 12 and another four Catholics died in an attack two days later in the northern town of Ouahigouya.