Ecuador's massive Cotopaxi volcano stirred in the early hours of Friday, with two explosions reported and ash raining down on the southern part of nearby highland capital Quito.
The Andean country's highest active volcano has been showing signs of activity since April, and Ecuador's Geophysical Institute said Friday's explosions were small.
The volcano is not erupting, the Institute stressed.
Still, authorities are monitoring the activity and the Institute issued a warning about one of the world's highest active volcanoes, popular with tourists.
"We recommend climbers take precautions around the crater, given the possibility of explosions which release rocks or energetic emissions of vapor and volcanic gases that could be harmful," it said in a statement.
The Environment Ministry closed the Cotopaxi National Park as a precaution.
The volcano is located around 50 km (31 miles) south of Quito and its snow-topped symmetrical cone, which rises to nearly 6,000 meters (19,685 ft), is visible from the capital on a clear day.
Images on social media showed cars and roads near the volcano covered in a light layer of ash.
The last eruption took place in 1940, according to the Smithsonian Institution's Global Volcanism Program.
Friday's minor explosions took place at 4.02 a.m. (0502 ET) and 4.07 a.m. local time, according to the Geophysical Institute.