Unidentified gunmen killed six people and wounded two others in an attack on a convoy from the Boungou gold mine in eastern Burkina Faso, the army said on Saturday.

Last week, five vehicles were dispatched from the mine, which is owned by Toronto-listed Endeavour Mining , to help a nearby convoy that had been stuck in the mud for days, the army statement said.

The attack occurred after the convoy was back on the road again. The assailants targeted the five support vehicles when they become separated from the convoy and its security detail.

“The five vehicles, for reasons which remain to be determined, remained behind the convoy, outside the security system put in place by the military,” the army said in a statement.

The attack underscores the dangers of operating in Burkina Faso, where since 2018 Islamist militants affiliated with Islamic State and al Qaeda have taken over large areas of the north and east, killing thousands and displacing over a million.

Thirty-nine people were killed in an ambush on buses filled with workers heading to the Boungou mine in 2019. Back then, the mine was owned by Quebec-based Semafo, which was acquired by Endeavour in 2020.

Workers at Boungou said that they had raised concerns about road safety months before the 2019 ambush.

When Endeavour restarted the mine, it said it would now be flying all personnel who did not live “within the immediate vicinity” of the mine to the site.