An explosion in northern Togo has killed seven people, the military said on Sunday, without giving further details about the blast.

The explosion happened in Tone prefecture near the border with Burkina Faso, where a Sahel jihadist insurgency is threatening to spill over into coastal West African nations.

Togo last month declared a state of emergency in its northern prefectures over the threat of Islamist militant attacks from north of its border.

Togo’s army said in a statement the explosion on Saturday in Margba village in Tone killed seven and wounded two more.

It did not give more details and did not describe it as an attack.

“An investigation is ongoing to determine the circumstances of this explosion and identify the perpetrators,” the army statement said.

Eight Togolese soldiers were killed in May in an attack in northern Togo near the border with Burkina Faso.

Togo’s troops are deployed in the north of the country to try and contain a jihadist threat pushing south from Mali, Burkina Faso and Niger where militants linked to Al-Qaeda and the Islamic State group operate.