Thousands of people living on the slopes of Mount Merapi in Indonesia are being taken to safety, because of fears the volcano may be about to erupt.
The elderly, women and children have been taken to emergency shelters after officials monitoring the volcano raised the threat status to the highest level.
The volcano has been rumbling for weeks but is becoming more volatile.
Streams of lava have been flowing down one side of the mountain, which is also spewing out hot volcanic ash and smoke.
However some villagers have refused to move because they do not want to leave their crops and livestock.
The lava has not reached any residential areas - but the BBC's Rachel Harvey in Indonesia says the authorities are not taking any chances.
"This morning we raised the status of Merapi to the top alert which is the red code," Subandrio, head of the Merapi section at the Centre for Vulcanological Research and Technology Development, said on Saturday.
Mount Merapi is in a state of "constant lava flow"
"Every resident has been ordered to evacuate."
Military trucks have been used to ferry thousands of people away from the danger zone.
Officials have been struggling to conduct mass evacuations as some villagers are reluctant to leave their valuable farmland.
Some residents told officials they are worried about their property, cattle and crops.
However on Saturday a resident told Reuters news agency by phone: "Everything ran smoothly, just like the exercises".
The scientists still cannot say when the volcano will erupt nor how powerful any explosion might be.
Merapi - which means "mountain of fire" - is now in a state of "constant lava flow".
A gas cloud from the volcano's last eruption in 1994 killed 60 people.
Local television has been showing dramatic night-time pictures of a stream of lava slipping down one side of the mountain.
But scientists warn that the greatest danger could come from hot gases expelled from the volcano's crater.
Vulcanologist Bambang Dwiyanto said the alert had been raised because "there has been constant lava flows that cause hot gases".
Indonesian Vice President Jusuf Kalla toured the area on Thursday and ordered 50% of the population in the danger zone be moved.
Indonesia, part of the Asia-Pacific "Ring of Fire", has at least 129 active volcanoes.
Mount Merapi, which some locals consider sacred, overlooks the ancient city of Jogjakarta.
One of its deadliest eruptions was in 1930, when about 1,300 people were killed.
Do you live in the area? Have you or do you know anyone who has been affected by the evacuation? Send us your experiences by using the form below:
I visited Marapi in 1994. What concerned me most was that the city of Jogjakarta has a population of over 10 million people. If Merapi was to erupt on a massive scale this could be one of the worlds greatest humanitarian disasters.Tim Butler, UK
I have friends in Indonesia and wish everyone is more willing to leave since the eruption is very dangerous and death is imminent. don't worry about life stock because they are replaceable but your life can't. The soil in the farmland will become much more fertile after the eruption.Sherwin Lo, Marietta, USA
I live 35 km to the east of mount Merapi. Luckily for me, the eruption never affect areas in the east of Merapi but only to the north and northwest. After the eruption, the sky will be very dark and it will rain of ash and dirt for about two hours. When I was a kid, the eruption didn't affect us directly but the whole town was covered by thick-gray-ash and we spent hours to sweep it off our roof and garden. Yesterday I heard that some poor farmers wanted the government to buy their cattle and livestock because it is the only possession they have. It's an old old story, EVERY TIME Merapi erupts, there are ALWAYS dead victims. Usually it's the ones who decided to stay in the Merapi's vicinity.Winarto, Solo, Indonesia
I am a Canadian who used to live in Yogyakarta 20 years ago. I fell in love with the people, the land and climbed Merapi. It was common to leave at dusk in order to watch the sunrise from the peak of Merapi. I stay in touch with my friends there who are nervous - remember this if from the land of Krakatoa and one only needs to think of Pompeii to realise what could happen. Spencer Campbell, Canada