The capital's worldwide airport has also been closed due to the danger the ash poses to planes.
Earlier on Sunday, the volcano spewed black smoke and ash into the sky, prompting the evacuation of about 100 people.
"We are evacuating and rescuing people and have reports of 20 wounded, six dead and disappeared", said Cabanas.
President Jimmy Morales said he had convened his ministers and was considering declaring a state of emergency in the departments of Chimaltenango, Escuintla and Sacatepequez.
This eruption is the biggest since 1974, according to local experts.
The river of lava has reportedly changed direction and is now heading toward a small town.
"It's a river of lava that overflowed its banks and affected the Rodeo village".
Sergio Cabanas of the National Disaster prevention committee spoke to Reuters and informed that people have been burned and killed including a member of his staff.
"Unfortunately El Rodeo was buried and we haven't been able to reach the La Libertad village because of the lava and maybe there are people that died there too".
One video published by news outlet Telediario, purportedly taken in the El Rodeo village, showed three bodies strewn atop the remnants of the flow as rescuers arrived to attend to an elderly man caked from head to toe in ash and mud.
Hundreds of rescue workers, including firefighters, police and soldiers, worked to help any survivors and recover any more bodies amid the still-smoking lava.
Search and rescue operations for the missing and dead have been suspended due to low light and unsafe conditions, and will resume early on Monday morning, the spokesperson said.
Officials have advised citizens to wear masks due to falling ash, which has been raining down in four of Guatemala's administrative regions.
The runway was closed due to the presence of volcanic ash and in order to guarantee passenger and aircraft safety, Guatemala's civil aviation authority said in a Tweet.
Guatemala's disaster agency said 3,100 people had evacuated nearby communities, and ash fall from the eruption was affecting an area with about 1.7 million of country's 15 million or so people.
The eruption of the 3,763-metre Volcan de Fuego - meaning "volcano of fire" in Spanish - was the most powerful in recent years, according to the National Institute of Seismology, Volcanology, Meteorology and Hydrology (Insivumeh).