The volcano named Fuego -- Spanish for fire -- rumbled into activity overnight Saturday into Sunday, with molten rock oozing down its slopes and ash belching two kilometers (more than a mile) into the sky.
A road that goes south from central Guatemala has been closed as a precaution, said Carlos Aquino, a spokesman for the highway police.
The volcano is about 16 kilometers (10 miles) from Antigua, the country's picturesque former capital and biggest tourist attraction.
Authorities are monitoring the volcano and so far no one has been evacuated, said Rodolfo Garcia, a civil protection spokesman.
Wind might push the ash plume toward Guatemala City, which is 35 kilometers away, he said.
In 2018, the Fuego volcano sent rivers of lava pouring down its sides, devastating the village of San Miguel Los Lotes, killing 215 people and leaving a similar number missing.
