The Democratic Republic of the Congo’s (DRC) Mount Nyiragongo has erupted for the first time in nearly two decades, sending lava sliding down the hillside towards the eastern city of Goma and forcing thousands of people to flee.

As the red glow of Mount Nyiragongo tinged the night sky above the lakeside city of about two million, Goma residents carrying mattresses and other belongings fled the city on foot on Saturday – many towards the border with Rwanda.

Nyiragongo’s last eruption in 2002 killed 250 people and left 120,000 homeless in the DRC. It is one of the world’s most active volcanoes and is considered among the most dangerous.

The smoking trail of lava from the eruption appeared to have halted a few hundred metres from the city’s edge, a source told Reuters news agency on Sunday.

Rwanda’s emergency management ministry said more than 3,500 Congolese crossed the border. Rwandan state media said they would be lodged in schools and places of worship.

Volcano watchers have been worried that volcanic activity observed in the last five years at Nyiragongo mirrors that in the years preceding eruptions in 1977 and 2002.

Volcanologists at the OVG, which monitors Nyiragongo, have struggled to make basic checks on a regular basis since the World Bank cut funding amid embezzlement allegations.