Authorities said at least 25 people were killed and 20 more injured, with fears the death toll could rise.
"Currently the volcano continues to erupt and there exists a high potential for (pyroclastic) avalanches of debris", the disaster agency said late Sunday via Twitter, quoting Sanchez, the director of the seismology and volcanology institute.
Some 3,100 people had been evacuated from the danger zone by Monday morning, with further evacuations planned.
The eruption forced the Guatemala City's La Aurora global airport to shut down its only runway due to the presence of volcanic ash and to guarantee passenger and aircraft safety, Guatemala's civil aviation authority said in a tweet.
La Aurora International Airport remains closed as a preventive measure because the runway was covered with volcanic ash.
Here's what the situation looks like on the ground.
The Red Cross is working closely with CONRED, Guatemala's national civil protection authority, and will activate its blood services and Restoring Family Links support to help with the response. About four hours later, lava began flowing down the side of the mountain.
"The landscape on the volcano is totally changed, everything is totally destroyed", government volcanologist Gustavo Chigna said on local radio.
El Rodeo resident Rafael Letran says the country's disaster agency sent pickup trucks with workers "yelling at people to leave". As hot molten lava flowed from the volcano's banks into small towns, people scrambled to escape. These volcanoes sit on the western edge of the Caribbean tectonic plate, along an active subduction zone.
In the village of El Rodeo, heavily armed soldiers wearing blue masks to ward off the dust stood guard behind yellow tape cordoning off the scene as orange-helmeted workers operated a backhoe.
On May 21 Paraguay became the third country to open its embassy in Jerusalem. Israel considers Jerusalem its capital. Palestinians seek East Jerusalem as their future capital and have been infuriated by the embassy moves.
At least 62 people were killed after the volcano erupted Sunday, spewing a river of lava and plumes of smoke nearly 6 miles into the air, said Mirna Celedon, spokeswoman for Guatemala's Institute of Forensic Sciences.
Residents should stay away from the still-dangerous area, said David de Leon, a spokesman for national disaster management agency CONRED.
At least another 20 people have been injured in the eruption, the second major one this year from the 3763 metre peak.
Volcán de Fuego (Volcano of fire) - one of the most active volcanoes in Central America - is located about 27 miles from Guatemala City.
Searing flows of ash mixed with water and debris gushed down the volcano's flanks, blocking roads and burning homes.