Dangerous flows of lava, ash and toxic gases have poured down several canyons below the crater of Guatemala's Fuego volcano, prompting a new round of evacuations of rescue workers and nearby villages.
At least 109 people have died in a series of eruptions that began with a massive blast last Sunday.
Ash has been showered over a vast area.
In two of the canyons where flows have accumulated, columns of ash rose as high as 6,000m (19,700ft), according to a statement from Guatemala's volcanic institute.
"The (flows) carry hot vapour, including fine particle similar to cement, two to three-metre diameter rocks and tree trunks dragged out by the current," the statement added.
The flows sparked panic among rescue workers still in the area, as well as volunteers and police.
Search and rescue efforts were formally suspended yesterday due to hazardous conditions, although authorities said they could resume if the situation improves.
Along a closed highway that connects the towns of El Rodeo and San Miguel los Lotes, around 25 people, many with picks and shovels, waited to resume the search for the missing.
The death toll from Fuego's most violent eruption in four decades has been gradually rising as rescue teams scoured the ravaged landscape, which is coated in ash.
The US government has said it is sending emergency aid at Guatemala's request, while Mexican authorities have sent doctors to help survivors with severe burns, at least seven of whom, in critical condition, were transferred across the border into Mexico.
The death toll from Fuego, which means "fire" in Spanish, is expected to rise further as more bodies are found.