Two people were killed and at least five injured when a volcano erupted at a tourist destination in Indonesia's East Java province.
The two men - one Indonesian and the other from Singapore - were hit by hot rocks expelled from Mount Bromo.
There are also fears that a separate volcano, Mount Awu, may erupt in the north-east of the country.
More than 15,000 people have been evacuated from the area, amid warnings of impending volcanic activity.
An eyewitness on Mount Bromo told the BBC she was forced to scramble down from the crater when the volcano began spewing rocks and dark smoke on Tuesday afternoon.
Few people live in the immediate vicinity of the volcano, but visitors to the region often climb its slopes to watch the sunrise.
Far more people live near Mount Awu, on Sangihe island, which began spewing ash and smoke last week.
"There is a lot of smoke coming out, and there are indications that it will erupt," a local official there said on Tuesday.
'Ring of Fire'
Those who have been evacuated from the slopes of Mount Awu have been taken to Tahuna, 15km (nine miles) to the south.
They are now sheltering in government offices and other public buildings.
More than 80% of residents in dangerous areas have now been evacuated, but some men have reportedly stayed behind to guard their villages.
Mount Awu is one of Indonesia's most active volcanoes, and has erupted repeatedly since the 17th century.
Nearly 3,000 people died when it blew up in 1812. The last major eruption was in 1966, when 40 people died and thousands were evacuated.
Indonesia is home to more than 100 active volcanoes, and minor eruptions are common.
It sits astride the geological fault line that runs around the rim of the Pacific Ocean, which is known as the "Ring of Fire".