GUATEMALA CITY -- The death toll is mounting after an explosive eruption of one of Central America's most active volcanoes. Guatemala's Volcan de Fuego, Spanish for "volcano of fire," exploded shortly before noon on Sunday, blasting ash and molten rock high into the air. Hours later, around 4 p.m., lava began flowing down the side of the mountain.

Guatemala's disaster agency said early Monday that at least 25 people had been killed as a towering cloud of smoke blanketed nearby villages in heavy ash and pyroclastic flows inundated villages below the volcano. An undetermined number of people were missing and authorities feared the death toll could rise.

Eddy Sanchez, director of the country's seismology and volcanology institute, said the lava flows reached temperatures of about 1,300 degrees. Firefighters said they were forced to call off rescue efforts until later on Monday morning over safety concerns.

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Video broadcast by Sacatepezuez television showed a charred landscape where a lava flow came into contact with homes. Three bodies lay partially buried in ash and debris from the volcano, which is about 27 miles from the capital, Guatemala City.

A volunteer firefighter carries a child after the eruption of the Fuego Volcano, in El Rodeo village, Escuintla department, south of Guatemala City, June 3, 2018. Getty

"Not everyone was able to get out. I think they ended up buried," Consuelo Hernandez, a resident of the village of El Rodeo, told the newspaper Diario de Centroamerica. "Where we saw the lava fall, we ran to a hillside" to escape, she added.

Hundreds of rescue workers, including firefighters, police and soldiers worked to recover bodies from the still-smoking lava.

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. In darkness and rain, the rescue effort was ordered suspended until early morning, municipal firefighters spokesman Cecilio Chacaj said.

Fuego volcano is pictured after it erupted violently, in San Juan Alotenango, Guatemala, on Sun., June 3, 2018. Reuters

National Disaster Coordinator Sergio Cabanas said seven people were confirmed dead and an unknown number were unaccounted for.

Among the fatalities were four people, including a disaster agency official, killed when lava set a house on fire in El Rodeo village, Cabanas said. Two children were burned to death as they watched the volcano's second eruption this year from a bridge, he added.

Another victim was found in the streets of El Rodeo by volunteer firefighters, but the person died in an ambulance.

At an ad-hoc morgue in the town of Alotenango, at least three bodies lay covered with blue sheets.

A man cleans ashes from the Volcan de Fuego off his car in Antigua Guatemala, Sacatepequez department, southwest of Guatemala City on Sun., June 3, 2018. Getty

Guatemala's disaster agency said 3,100 people had evacuated nearby communities, and ash fall from the eruption was affecting an area with a population of about 1.7 million of the country's 15 million or so people. Shelters were opened for those forced to flee.

"Currently the volcano continues to erupt and there exists a high potential for (pyroclastic) avalanches of debris," the disaster agency said via Twitter, quoting Sanchez, the director of the seismology and volcanology institute.

It added that he said authorities began to send bulletins on the situation starting at 11:30 a.m.

Guatemalan President Jimmy Morales said he would issue a declaration of a state of emergency to be approved by Congress and urged people to heed warnings from emergency officials.

Volcan de Fuego Guatemala Government via BBC News

Ash was falling on the Guatemala City area as well as the departments of Sacatepequez, Chimaltenango and Escuintla, which are in south-central Guatemala around the volcano. Streets and houses were covered in the colonial town of Antigua, a popular tourist destination.

Aviation authorities closed the capital's international airport because of the danger posed to planes by the ash.

BBC News reports officials advised residents to wear masks as ash fell. The news outlet also said the Guatemalan military was providing help which includes clearing volcanic ash from La Aurora airport's runway.

The conical Volcan de Fuego reaches an altitude of 12,346 feet above sea level at its peak.