Fuego's eruption is the biggest since 1902, when the Santa Maria volcano erupted, killed thousands of people.
Initial reports put the death toll at seven, but authorities say they found 18 more people later Sunday in the community of San Miguel Los Lotes.
The head of Guatemala's disaster agency said 33 people have been confirmed killed in the volcano's eruption, and the death toll is expected to rise further.
Volcan de Fuego, whose name means "Volcano of Fire", spewed an eigth-kilometre stream of red-hot lava and belched a thick plume of black smoke and ash that rained onto the capital and other regions.
Searing flows of ash mixed with water and debris gushed down the volcano's flanks, blocking roads and burning homes. Temperatures in the lava flow reached 1,300 degrees Fahrenheit, according to Eddy Sanchez, director of the country's Seismology and Volcanology Institute.More news: Long wait over for Goldolphin as Masar wins Derby
Using shovels and backhoes, emergency workers dug through the debris and mud, perilous labor on smoldering terrain still hot enough to melt shoe soles a day after the volcano exploded in a hail of ash, smoke and molten rock. Local media reported that the ash blanketed cars and houses in villages nearby.
"Not everyone was able to get out".
"We were at a party, celebrating the birth of a baby, when one of the neighbors shouted at us to come out and see the lava that was coming", the distraught woman said.
After evacuating the town of El Rodeo with his family, he returned to search for his son and daughter-in-law. Firefighters said they had seen some people who were trapped, but roads leading to the area were cut by pyroclastic flows and they had been unable to reach it.
Local search and rescue efforts were suspended on Sunday due to low light and unsafe conditions.
National Disaster Coordinator Sergio Cabanas said an undetermined number of people were missing following the eruption of the Volcan de Fuego, Spanish for "volcano of fire", which lies 44 kilometers (27 miles) from Guatemala City.More news: Duchess of Sussex: Meghan to accompany Queen for first time
Another victim was found in the streets of El Rodeo by volunteer firefighters and died in an ambulance.
At an ad-hoc morgue in the town of Alotenango, at least three bodies lay covered with blue sheets.
Residents of several communities rest in a temporary shelter in Escuintla department south of Guatemala City on June 3, 2018.
Survivors described the horror and destruction when the volcano erupted.
President Jimmy Morales was to hold a news conference late Sunday, while officials were telling residents in the area to remain calm.
The volcano is some 40 km southwest of the capital, Guatemala City, and is close to the colonial city of Antigua, which is popular with tourists and is known for its coffee plantations.
Dense ash blasted out by the volcano shut down Guatemala City's global airport, civil aviation officials said.More news: Toure accuses Guardiola of 'not liking African players'
This is the second time in 2018 that Fuego, one of Latin America's most active volcanoes, has erupted.