KHARTOUM, Sudan — Their temporary headquarters are a beehive of young volunteers buzzing in and out of rooms, up and down stairs, carrying bags of donated food, medicine and large packets of plastic sheets.

“What happened to your house?” one volunteer asks on the phone, as others load aid on trucks or create maps and charts on laptops. “And where do you say you are? We’ll have a team out there soon.”

They are the members of Nafeer, a volunteer, youth-led initiative that responded swiftly to the humanitarian crisis caused by heavy rains and flash floods that struck Sudan this month.

The deluge has taken a heavy toll. Beyond the dozens of people killed, more than 300,000 people have been directly affected, with 74,000 homes damaged or destroyed, according to the United Nations. The spread of diseases like malaria is also reported to be on the rise.