GOMA, Congo -- Thick lava streamed through the abandoned city of Goma on Friday, burning everything in its path, and steam rose above Lake Kivu after a volcano spewed rivers of molten fire that destroyed at least half the city.
Hundreds of thousands of people fled the devastation, many into Gisenyi in neighboring Rwanda. Exhausted men, women and children carrying rolled up mattresses and cooking pots slumped together on the road clogged with vehicles heading to Gisenyi.
Officials were trying to determine the number of casualties amid concerns there could be many dead.
The night sky glowed scarlet from the fires in Mount Nyiragongo, 30 miles to the north, and international aid workers abandoning the city said they were afraid the large quantities of methane gas that exists naturally in the lake would explode.
There was no information yet on deaths or injuries, said Stephen Johnson, an official in the U.N. office for the coordination of humanitarian affairs in New York.
There were no indications the eruptions that began Thursday had finished, he said.
"Goma has been split completely in half, and one half is totally destroyed, burned," he said.
Johnson said about 100,000 people had fled west into Congo, while 300,000 others crossed over to Rwanda in the east.
He said the smoke and ash had made it difficult to judge the damage, so his office was awaiting the assessment of an interagency mission on the ground.
"This is terrible, my children have all disappeared, and I am confused and shocked," said Mulili Flaha, a Goma housewife who fled to Gisenyi on Thursday night when a dark, thick layer of lava approached her house. Her husband and five children all ran in different directions.
Adolphe Onusumba, head of the Rwandan-backed rebels who control Goma and the surrounding region, implored residents not to try to return to their homes.
"We are declaring a state of emergency and urge people not to return to their homes because of the losses," he said in a radio broadcast from the devastated city.
The disaster is taking place in an area where the population is already vulnerable from past conflicts and water shortages, Johnson said.
"Right now, we have no office or home because they were destroyed by the lava," said businessman Eloi Mboso Kiamfu as he prepared to leave for Gisenyi. "Goma almost does not exist anymore."
Brian Baptie, a volcano seismologist at the British Geological Survey in Edinburgh, Scotland, said Nyiragongo is one of the most active volcanos in Africa.
"Although the lava moves quite fast going down the flanks, once on flat land it moves quite slowly so people can get out of the way if they have warning," he said. "It's the refugee problem created that's the big cause for concern."
Florian Westphal, regional spokesman for the International Committee of the Red Cross, said two of the three water purification plants in the city of an estimated 500,000 inhabitants were no longer operational.
"We discussing how to best assess this situation," Westphal said. "Is it even safe to stay in the region?"
A large explosion had destroyed the main fuel depot at the port on the north end of Lake Kivu, he said.
In Brussels, Belgium, European Union spokesman Michael Curtis said EU relief experts were on the ground to assess what emergency aid would be needed and it was likely that food supplies and shelter materials would be the first priority.
"We can take a decision within 72 hours of a disaster," he said.
Basil Lukuba, a 24-year-old student who fled to Gisenyi, said people didn't know what to do because Radio Goma initially said the lava was flowing east toward Rwanda, away from the city.
"But a few hours later we saw terrible fires coming toward us. Most houses were burning, and everyone was on the run," he said.
The United Nations has sent several thousand military observers and peacekeepers into Congo following a cease-fire in the civil war that broke out in August 1998 in Goma.
A U.N. official who evacuated civilian and military staff from Goma to the Rwandan capital, Kigali, said the deputy force commander, Gen. Roberto Martinelli, arrived there Friday and would travel to Gisenyi and Goma on Saturday to assess the situation.
Britain said Friday it will give $2.9 million to help the volcano's victims.