The international aid effort has included teams from Egypt, Algeria, Tunisia, Turkey, Qatar, and the United Arab Emirates.
The International Organization for Migration said Wednesday the flooding displaced at least 30,000 people in Derna as well as thousands more in other areas.
Atiyah Alhasadi, a 30-year-old teacher from Derna, told VOA's Heather Murdock he was in his home in the center of the city when he heard what sounded like "20 million drums exploding," and the water crashed in, rising 50 meters above the houses.
Alhasadi said he and his family went to the roof of the building because the lower floors were flooded immediately and watched the water rise to the fourth or fifth floors of some buildings. He said his two aunts on the first floor died in the initial rush of water but his family was able to escape to a relative's home on higher ground.
Now, he said, he is with five or six families in one small house, searching for a vehicle to get to Benghazi or another town.
"We can't find gasoline, fuel, or water," he said.
Alhasadi said people also need mattresses and medicine but there is no available humanitarian aid to be found. He noted people are sleeping on the streets without even tents and the only hospital is barely functioning. It was just a makeshift hospital, while the actual one was under construction.