Thirteen park rangers and four civilians were killed by an unidentified armed group Friday in an attack in the Virunga National Park in the Democratic Republic of Congo, according to authorities.

The killing took place when a convoy of civilians protected by rangers was ambushed by suspected rebels operating in the park in Rutshuru territory, 50 kilometers (31 miles) from Goma, according to the Congolese Institute for the Conservation of Nature (ICCN).

The rangers were killed while trying to assist civilians who had fallen into the ambush, ICCN Director General Cosma Wilungula told reporters.

“We lost 13 park wardens in a rebel attack. Our guards were not the target but had intervened after hearing gunshots on a civilian convoy,” he said.

Wilungula attributed the attack to Rwandan rebels of the Democratic Forces for the Liberation of Rwanda (FDLR), operating in the area.

“The guards found about 60 FDLR rebels had surrounded the area. Our men died trying to assist civilians,” he said.

The attackers also burned a passenger vehicle.

Wilungula said four other rangers were seriously injured in the attack and were rushed to a local hospital.

The Virunga National Park, a UNESCO World Heritage site, is habitat for mountain gorillas, a popular tourist attraction.

The park spreads to Rwanda, DR Congo and Uganda and measures more than 7,800 square kilometers (4,846 sqare miles).

Visits to the park were suspended in March for 30 days due to the ongoing COVID-19 lockdowns in the three countries.

In 2018, a ranger was killed when gunmen killed two British tourists in the park, forcing authorities to suspend visits for most parts until early 2019.

DR Congo forces launched operations against armed groups in the eastern part of the country at the end of October.

More than 300 members of the FDLR surrendered to the Congolese army with weapons in the Kalehe region of South Kivu province after their base in Kahuzi-Biega National Park was destroyed in December. (Anadolu Agency)