Up to 170 children are missing and 15 people are dead after torrents of lava poured into villages after dark in eastern Congo with little warning, causing chaos and destroying more than 500 homes.

The eruption of Mount Nyiragongo on Saturday night sent about 5000 people fleeing from the city of Goma across the nearby border into Rwanda, while another 25,000 sought refuge to the northwest in Sake.

On Sunday, the United Nations children’s agency said at least 170 children were still feared missing, and UNICEF officials said they were organising transit centres to help unaccompanied children after the disaster.

Goma ultimately was largely spared the mass destruction caused by the volcano’s last eruption in 2002.

Hundreds died then and more than 100,000 people were left homeless.

But, in outlying villages closer to the volcano, Sunday was marked by grief and uncertainty. The air remained thick with smoke as dozens of homes had caught fire when the lava came.

Pope Francis took to Twitter to pray for lives lost: “Let us also pray for the populations of the city of Goma, in the Democratic Republic of Congo, forced to flee due to the eruption of the great volcano, Mount Nyiragongo”.

Tweet from @ItsDavidMaina

Elsewhere, authorities said at least five other people had died in a truck crash while they were trying to evacuate Goma, but the scale of the loss had yet to be determined in some of the hardest-hit communities.

According to the national broadcaster RTNC, residents reported there was little warning before the dark sky turned a fiery red, sending people running for their lives in all directions.

One woman went into labour and gave birth while fleeing the eruption to Rwanda.

RTNC said people were advised to take just five litres of water with them, a raincoat, sweater and some sugar. Doctors and medical personnel were urged to stay behind at the hospitals.

Lava from the eruption of Mount Nyiragongo is seen on the outskirts of DR Congo’s main city, Goma. Photo: AAP

In nearby Buhene, smoke rose from smouldering heaps of lava as witnesses described how lava had engulfed one highway connecting Goma with the city of Beni.

The airport appeared to be spared the same fate as 2002 when lava flowed onto the runways.

Goma is a regional hub for many humanitarian agencies in the region, as well as the UN peacekeeping mission. While Goma is home to many UN peacekeepers and aid workers, much of surrounding eastern Congo is under threat from myriad armed groups vying for control of the region’s mineral resources.

-with agencies