Rescue teams working to find survivors from a volcanic eruption in Guatemala paused their search following warnings of falling ash.

Guatemala’s national disaster agency said on Thursday, June 7, that hot volcanic material is making it dangerous for rescuers. Seventy-two hours have also passed since Sunday’s eruption, so the chance of finding any survivors is extremely unlikely.

As of Thursday, the death toll stood at 109 though nearly 200 more are believed to be missing.  

Guatemala’s Fuego volcano spewed hot lava and sent a column of ash nearly 10 kilometers into the sky, sending local residents running for the hills.

Officials reportedly said a lack of communication between the disaster agency and volcano experts delayed evacuations.

The U.S. is sending emergency aid, including financial resources, to help with food, water and sanitation and Guatemalan President Jimmy Morales has promised to release government funds to help with reconstruction.