Rebels in eastern Congo ambushed a stalled civilian convoy that was under military escort Wednesday, killing five people and abducting dozens of hostages initially. About 20 people remained missing hours later, the army said.

The attack took place after the convoy had stopped to repair one of the vehicles, Capt. Jules Ngongo, spokesman for the Congolese army in Ituri province, told The Associated Press.

Initially the gunmen kidnapped 80 people but he said the army was able to soon rescue 60 of them.

“We call on people to remain calm and to trust their army because it is difficult to fight the terrorists, but we will fight for peace to return as soon as possible,” Ngongo said.

The latest attack, though, prompted more outcry in eastern Congo, where civilians say the rebel group known as ADF is stepping up its attacks.

“What is the purpose of our army? How can a convoy of civilian vehicles be attacked when they were secured by the army? Without capturing even one rebel?” said Christian Munyanderu, coordinator of a local human rights group.

The ADF, or Allied Democratic Forces rebels, trace their origins to nearby Uganda and have long carried out attacks in eastern Congo, at times bringing gunfire to the city center of Beni.

The ongoing attacks there have repeatedly prompted anger about the inability of the Congolese army and U.N. peacekeepers to stop the violence.

Fears have deepened ever since ADF reportedly pledged its allegiance to the Islamic State organization though the exact ties between the two groups remain murky.

Islamic State’s Central Africa Province claimed a suicide bombing at a busy intersection in Beni earlier this year. The Ugandan man died, but no one else was killed in that blast believed to be the first of its kind in eastern Congo.