Guatemala's disaster agency is calling for calm, but after receiving little or no warning before the volcano exploded Sunday, many people are not taking chances.
At least 75 people are dead and 192 are missing due to the eruptions, which have also halted rescue missions as search crews were forced to evacuate.
Sunday's blast generated pyroclastic flows - fast-moving mixtures of very hot gas and volcanic matter - which descended down the slopes, engulfing communities including El Rodeo and San Miguel Los Lotes.
He said that local residents had received training in emergency procedures, but were not able to implement them because the initial volcanic activity happened too fast.
"President Buhari considers Guatemala as one of the closest allies Nigeria has in Central America and will, therefore, always share and identify with any development, progress or tragedy, with the government and the people of Guatemala", the letter said.
Guatemala's disaster agency says superhot volcanic material is once again flowing down the south side of the Volcano of Fire.
People were killed inside their homes as a result. There are many people who are helping us, but we have absolutely nothing.
An elderly man, who was featured in a video shortly after the eruption that showed him in a state of shock, caked from head to toe in ash and mud, died from the severe burns he suffered. Rescuers, police and journalists hurried to leave the area as a siren wailed and loudspeakers blared, "Evacuate!"
A volcanic flow swept through El Rodeo and San Miguel Los Lotes on Sunday, burying homes up to rooftops.
Guatemala's National Institute of Forensic Sciences has raised the death toll from Sunday's eruption of the Volcano of Fire to 75. Numerous victims are unrecognisable, with officials warning that DNA testing and other methods may be needed to identify them.
Authorities say at least 46 people were injured in the eruption, and 12 shelters were housing 1,877 people.
Guatemala's Volcano of Fire is continuing to burst out rocks and ash, almost two days after a major eruption that killed at least 69 people.
General Walter Sanchez, in charge of operations around the epicenter of the destruction near the village of El Rodeo, said the heat from the ash and hot sediment made rescue work hard.