Rescue workers seeking to reach people who desperately need help in earthquake-ravaged Nepal face myriad obstacles — and the weather is only making things worse. In the district of Gorkha, where the 7.8-magnitude quake was centered, a large storm rumbled over the mountainous terrain Tuesday afternoon. “There was thunder and lightning — water was rushing down the road where I was standing,” said Matt Darvas, an emergency communications officer for the humanitarian group World Vision. “That essentially shut down helicopter missions for the entire afternoon, except for a small window before sunset,” Darvas, who’s currently in the main town in Gorkha, told CNN on Wednesday.

The canceled helicopter flights meant fewer airdrops of vital supplies to devastated villages and dashed hopes of rescues for injured people in isolated locations. Nepalese authorities have so far said 5,016 people died and more than 10,000 were injured as a result of the massive earthquake that struck Saturday. But officials have warned the death toll is expected to rise. Two neighboring countries, India and China, have reported totals of 72 and 25 deaths from the quake, respectively. The frequent downpours in Nepal have made it harder for emergency workers to help the injured. CNN’s Dr. Sanjay Gupta was at an army field hospital in Kathmandu, the capital, when the heavens opened Tuesday. “The rain has arrived and in many cases this is the worst-case scenario,” he said. “This is what they were hoping wouldn’t happen.” Pieces of tape held patches in the ceiling as water threatened to bubble in; sheets of canvas served as walls. Gupta said it was “kind of remarkable what they’ve been able to do” at the makeshift hospital. Over three days, the medical staff there had treated 617 patients and saved 586 of them. MORE