LONDON -- Mozambique's president declared three days of national mourning on Wednesday as the southeast African country struggles to recover from a powerful cyclone that has claimed hundreds of lives, submerged villages and washed away homes.
As the scale of devastation widens, aid agencies said it might be the worst cyclone-related disaster ever in the Southern Hemisphere.
"The situation is very bad. The damage is quite serious," Katharina Schnoering, head of the United Nations' migration agency in Mozambique, said in a statement Wednesday. "It Is very difficult to get a clear overview of what is going on. There are many communications issues, there’s no power in Beira. There is no road access because the Buzi River came up and washed out the road."
An estimated 1.7 million people were in the cyclone's path in Mozambique, which bore the brunt of the storm, while another 920,000 people in Malawi and "thousands more" in Zimbabwe were also affected, according to World Food Program spokesperson Herve Verhoosel, who told reporters Tuesday that "the biggest challenge" is accessing those in need.
Verhoosel said World Food Program staff members who flew over areas flooded by swollen rivers spoke of "inland oceans extending for miles and miles."
So far, the storm has been blamed for the deaths of more than 200 people in Mozambique alone, according to Mozambican President Filipe Nyusi, who has warned that as many as 1,000 people could be dead.
At least 89 deaths have been reported in Zimbabwe and 56 deaths in Malawi, according to government officials.
Some 400,000 people were internally displaced by the storm in Mozambique, while an estimated 82,500 were displaced in Malawi. In Zimbabwe, close to 1,000 homes were destroyed in the eastern districts of Chimanimani, Chipinge, Mutasa, Mutare, Buhera, Chikomba, Gutu and Bikita, according to the United Nations.
Paolo Cernuschi, the International Rescue Committee's country director for Zimbabwe, said "the impact of this disaster cannot be underestimated and will require our attention for many months to come."
"We are expecting the situation to worsen and to see a surge in malaria and other water borne diseases," Cernuschi said in a statement Wednesday. "Further, this disaster compounds an already dire situation as the hardest-hit areas were facing severe food insecurity and economic hardships prior to the cyclone. Whatever crops that were being grown despite the drought have now been destroyed in the floods."
Deborah Nguyen, a communications adviser for the World Food Program, is part of the response in Mozambique's hard-hit Beira, a coastal city of half a million people where 90 percent of buildings were damaged, including the World Food Program's warehouse and port unloading machinery as the agency works to distribute 20 metric tons of high energy biscuits. The cyclone also knocked out telephone and internet communications across the city, which Nguyen said is "completely under water."
"It's a very sad, desperate scene," Nguyen told ABC News in a telephone interview Tuesday. "All the trees are down. Power lines are down. So it's a very, very apocalyptic scene in Beira right now."
Nguyen said she was particularly moved by a conversation she had with a local resident, a mother.
"She was so traumatized by the cyclone that she couldn't think of a name to give to a baby boy," she told ABC News.
The cyclone has affected at least 260,000 children in Mozambique, according the United Nations International Children's Emergency Fund.
"Many children will have lost their homes, schools, hospitals and even friends and loved ones," said Leila Pakkala, UNICEF's regional director for eastern and southern Africa.
Heavy rain persisted over Beira and other parts of Mozambique on Wednesday, and more is forecast in the coming days, according to the World Meteorological Organization. Aid agencies worry the additional rainfall will impede the humanitarian response.
Mozambique's president on Wednesday declared a national state of emergency, describing the situation as "critical." But Nyusi said he has "faith" his country, with its "strength and determination" as well as the solidarity of others, will be able to rebuild the devastated areas.
ABC News' David Rind contributed to this report.