Zimbabwe is retrieving and burying bodies Wednesday as Mozambique begins three days of national mourning for victims of Cyclone Idai, one of the most destructive storms southern Africa has experienced in decades.

The death toll is rising in both countries, but the full number of those killed and the extent of damage done will only be known when torrential floodwaters recede. Persistent rains are forecast through Thursday so it will be days before the plains of Mozambique drain toward the Indian Ocean.

Zimbabwean President Emmerson Mnangagwa received a sombre welcome when he arrived at the hard-hit mountain community of Chimanimani on the eastern border with Mozambique. Some 300 people may have died in Zimbabwe as a result of the cyclone, say officials.

Some Zimbabwean bodies have been swept by rivers down the mountainside to Mozambique, according to officials.

Mozambican officials say its death toll is 200 and rising. President Filipe Nyusi said earlier this week he expects fatalities to be more than 1,000.

“Some of the peasants in Mozambique were calling some of our people to say ‘We see bodies, we believe those bodies are coming from Zimbabwe,”‘ said July Moyo, Zimbabwe’s minister of local government.

Families congregated in Chipinge town, near Chimanimani, hoping to find ways to get to impassable areas where they expected to find bodies of relatives.

Churches, companies and individuals have donated clothes, food and other supplies to families that lost their homes.

International aid trickling in

International aid has started trickling in to ease the humanitarian crisis.

“Everyone is doubling, tripling, quadrupling whatever they were planning,” said Caroline Haga of the Red Cross in Beira, Mozambique, referring to supplies and aid workers. “It’s much larger than anyone could ever anticipate.”

Matthew Pickard of the humanitarian organization CARE said the response to Idai has been similar to prior natural disasters. Local authorities and international non-governmental organizations worked their way to the area in the first days, with additional aid destined to arrive soon after.

A man stands next to the wreckage a vehicles washed away on Monday in Chimanimani, eastern Zimbabwe, after the area was hit by the cyclone Idai. (Zinyange Auntony/AFP/Getty Images)

The slow-moving catastrophe of the flooding and the inability to access some of the hardest-hit areas has limited the ability of some to see the scale of the cyclone. But, Pickard said, as those details become clearer, aid will spike.

“Over the next few days we’ll learn just how big it is,” he said by phone from Lilongwe, Malawi. “These are countries that are not usually making headlines and they’re making headlines. With the story comes people’s intent to respond empathetically.”

Sacha Myers of the non-profit Save the Children, speaking from Maputo, Mozambique, described rising floodwaters, “rivers and dams bursting their banks” and a death toll in the hundreds that was destined to climb.

She was awaiting the arrival of a cargo plane carrying emergency supplies, but said getting them where they needed to go remained difficult with roads washed away or submerged and few options for storage in dry areas.

“We’re having an unfolding crisis that’s getting worse and worse,” she said.

The United Nations was deploying resources too, deputy spokesman Farhan Haq said, but logistics remained challenging and the hardest hit areas, including Chimanimani, Zimbabwe, remained inaccessible.

An elderly woman washes her belongings in the mud in Chimanimani on Tuesday. (Zinyange Auntony/AFP/Getty Images)

As better data emerges from the disaster zone, donors will be standing by to make money and other resources such as medicine available, said Dr. E. Anne Peterson of the non-profit health organization Americares.

“It’s early and a really big disaster gets attention fast, and the more media covers it, the more people realize there is a need and the more likely we are to see them getting engaged,” she said.

Ilan Noy, chair in the economics of disasters at Victoria University of Wellington, New Zealand, said aid was likely to flow from dozens of countries to the African nations. How much is pledged and when, he said, correlates to the media coverage a given disaster gets, not to mention factors such as the geostrategic interests and previous colonial ties of an affected country. Ultimately, the dollar figures that are announced can bear little meaning, with the numbers typically stand-ins for the value of salaries and supplies sent overseas.

“They don’t have enough helicopters or they don’t have enough doctors,” Noy offered as an example. “In that emergency phase, it doesn’t really matter how you count it. You need resources. You don’t need cash.”