Search crews have returned to the Ouachita Mountains on horseback and all-terrain vehicles, hoping to find campers who survived the flash flooding of their camp grounds along the Caddo and Little Missouri rivers.
Other searchers in canoes and kayaks are exploring river banks for bodies that may have become tangled in the brush.
The search is expected to take several more days and perhaps even weeks.
"Portions of the river[s] that need to be searched have been divided," Renee Preslar, of the Arkansas Department of Emergency Management, told Al Jazeera.
"We're focusing on saving lives but also on the call centres we have activated."
Her department is reported to have sent satellite phones and specialised radio equipment to the stricken area to help in the rescue effort.
Portable mobile-phone towers are being dispatched in hopes of allowing stranded survivors to get reception and call for help.
"Right now, the area that was heavily flooded is very hot and humid, which doesn't make the search very pleasant. However, we're not here to feel comfortable," Preslar said.
"They're out there to save lives and that's what we're here to do."
|Up to 300 people may have been in the camp site when a torrent of water struck [Reuters]
Tabitha Clarke, a hydrologist with the National Weather Service, believes the rough terrain is keeping some campers from reaching safety.
Some parts of the valley are so steep and craggy that the only way out is to hike downstream.
Any hikers who had taken cars to the campsites would have been blocked at low-water bridge crossings that are inundated when the rivers rise, Clarke said.
Heavy rains had caused the normally quiet rivers to burst their banks during the night.
At around dawn, floodwaters surged into the Albert Pike Recreation Area that was packed with vacationing families.
The American Red Cross says as many as 300 people could have been in the camp site located in southwestern Arkansas when the storm swept through.
Two dozen people were hospitalised and 60 others were rescued.
However, the records of who was there had been washed away in the flood, making the daunting search for dozens of missing in heavily wooded forest even more difficult as anguished families waited for word of their loved ones.
The torrent poured through the valley with such force that it stripped asphalt off roads and bark off trees.
Cabins dotting the river banks were severely damaged and mobile homes lay on their sides.