Meanwhile Guatemalan authorities confirmed the death toll from Sunday's eruption of the Volcano of Fire at 69, but said only 17 of the dead have been identified so far.
National disaster agency CONRED ordered evacuations and said that hot gas and molten rock were streaming from the volcano, which produced its biggest eruption in more than four decades on Sunday, showering ash on a wide area and sending lava flows through nearby towns.
The explosions billowed ash more than 5,000m (16,000ft) above sea level, with Guatemala's seismology and volcanology institute warning that there is a moderate flow of unsafe material down the volcano - with the possibility of a strong flow in some areas.
By afternoon a new column of smoke was rising from the mountain and Guatemala's disaster agency said volcanic material was descending its south side, prompting an evacuation order and the closure of a nearby national highway. It warned civil aviation authorities to closely monitor and take precautions regarding air traffic.
Rescuers, police and journalists hurried to leave the area as a siren wailed and loudspeakers blared, "Evacuate!"
Volcanologists said earlier on Tuesday that the initial eruption, which sent ash up to 10km (33,000ft) into the sky, was over for the near future.
"My respects to you heroes without cloak", one said.
The institute said there was a moderate flow of risky volcanic material down the volcano, and warned of the possibility of a strong flow in some areas.
Officials say a total of 192 people remain missing, but the search for bodies in mountainous areas destroyed by the eruption has been progressing slowly.
Families of victims of the devastating volcanic eruption in Guatemala have been returning to the communities around the Fuego volcano to look for the...
The chance of finding additional survivors in the affected area is also dwindling, according to CONRED spokesperson Juan Sanchez. The city has survived several major eruptions.
The country's volcanology and meteorology institute says the volcano has been experiencing eight to 10 moderate explosions per hour Tuesday morning, though the scale of the activity is far lower than that of Sunday.
Rescuers have struggled to reach rural residents cut off by the eruption, which has killed dozens at least.