The country’s vulcanology institute said that three rivers of lava were also emerging from the crater and flowing down the sides of the mountain.
Fuego had previously sent pyroclastic flows of searing debris cascading down its slopes on May 19 and May 25.
Other than briefly being a hazard to aviation, the recent eruptions have not posed a threat to any nearby inhabited areas.
Guatemala has four active volcanoes that have caused catastrophic damage in the past.
The explosive eruption of Santa Maria in 1902 was one of the world's largest eruptions of the 20th century.
In 2010, a blast at Pacaya volcano coated the current capital, Guatemala City, in a thick layer of ash and rock.
This forced hundreds of families to evacuate and officials to temporarily close the international airport.
Photo: National Coordinator of Disaster Reduction