GUATEMALA CITY — One of Central America’s most active volcanoes erupted in fiery explosions, killing at least six people and injuring at least 20 while a towering cloud of smoke blanketed nearby villages in heavy ash.

Guatemala’s national disaster coordinator, Sergio Cabañas, said an undetermined number of people were missing following the eruption of the Volcán de Fuego, about 30 miles from Guatemala City.

Four people, including a disaster agency official, were killed when lava set a house on fire in El Rodeo village, Mr. Cabañas said, and two children were burned to death as they watched the volcano’s second eruption this year from a bridge.

David de León, spokesman for the disaster agency, said about 300 people had evacuated the area around the volcano.