Agencies, Lumajang, East Java – Thousands of villagers living near Mount Semeru were racing for refuge Sunday to the wail of emergency sirens as lava snaked towards their homes under a black sky after the volcano erupted.
Locals fled on motorbikes sometimes three at a time as a mushroom cloud of ash approached and monsoon rains lashed the area in East Java.
"It was dark and raining. The rain did not consist only of water, but also volcanic ash. It was like mud," said an AFP journalist on the scene.
Indonesian authorities raised their alert level for the volcano to its highest after the crater spewed hot ash a mile into the sky.
It came only a year after the volcano last erupted, killing at least 51 people and laying waste to homes.
Rescue workers were once again rushing to evacuate villagers in the area Sunday as a colossal plume of ash engulfed all light.One emergency responder, Gunawan, filmed the clouds above as a midday sky turned ominously dark as though midnight.
"It's getting dark, bro," he said to the camera as a seismograph whistled in the background.
The internet was down and phone signals were patchy but villagers were alerted to the danger by sirens and the beating of bamboo drums by local volunteers.
Semeru is the highest mountain in Java and lies around 800 kilometres (500 miles) southeast of the capital Jakarta among a cluster of craters in a moon-like landscape.
The eruption last year left locals combing through ruined belongings after their homes were blanketed in ash.
It remains to be seen what damage the eruption will inflict this time with the lava still edging towards homes and their owners told to remain eight kilometres (five miles) from the crater.
Many villagers, mostly women and children, took shelter in local halls and schools, some as far as 20 kilometres (12 miles) away.
Gunawan said everyone was safe for now, even if their possessions and homes might not be by day's end.
As he flashed a peace sign at a camera against the backdrop of dark haze and monsoon rains at his rescue post, he tried to reassure people.
"Salam tangguh, salam presisi!" he said, meaning "cheers", his voice relaxed but muffled behind a gas mask.
There were no immediate reports of any casualties from the eruption of the Semeru volcano and Indonesia's transport ministry said that there was no impact on air travel but notices had been sent to two regional airports for vigilance.
"Most roads have been closed since this morning and now it is raining volcanic ash and it has covered the view of the mountain," community volunteer Bayu Deny Alfianto told Reuters by telephone from near the volcano.
The National Disaster Mitigation Agency (BNPB) said 1,979 people had been moved to 11 shelters and authorities had distributed masks to residents. The eruption began at 2:46 a.m. (1946 GMT on Saturday) and rescue, search and evacuation efforts were going on.
The volcano's plume of ash reached a height of 50,000 feet (15 km), said Japan's Meteorology Agency, which had initially been on alert for the possibility that the volcano could trigger a tsunami. It later ruled that out.