Latest update: A small Christmas service was held near a stretch of Indonesia's tsunami-struck coastline Tuesday, as panicked residents in one coastal town tried to flee after rumours spread that another deadly wave was about to smash into the coast.
It turned out to be a false alarm, but widespread fears about a repeat disaster - and warnings that clean water and medicine supplies were running low - rippled across the region as the death toll from Saturday's volcano-triggered disaster topped 400.
Thousands more have been displaced, with many left homeless after houses were flattened by the killer wave.
"A lot of the children are sick with fevers, headaches and they haven't had enough water," said Rizal Alimin, a doctor working for NGO Aksi Cepat Tanggap, at a local school that was turned into a temporary shelter.
"We have less medicine than usual ... It's not healthy here for evacuees."
The powerful tsunami struck at night and without warning, sweeping over popular beaches on southern Sumatra and the western edge of Java and inundating tourist hotels and coastal settlements.
The latest death toll stood at 429, with 1,485 people injured and another 154 still missing.
Dec 24: The death toll from a volcano-triggered tsunami in Indonesia has risen to 373, with more than 1,400 people injured, the national disaster agency said Monday.
Some 128 were still missing following Saturday's volcano-triggered tsunami that hit southern Sumatra and western Java.
Earlier in the day the death toll was reported to be 281, as rescuers using heavy machinery and their bare hands searched through debris in the hope of finding survivors.
Indonesia’s meteorological agency confirmed the collapse of part of Anak Krakatau, a volcano midway between Java and Sumatra, caused a tsunami 2-3 metres high that hit the rim of the Sunda Strait late on Saturday.
At least 1,000 people were injured and nearly 12,000 coastal residents forcibly evacuated to higher ground, with a high-tide warning extended to Wednesday.
Anak Krakatau, which means child of Krakatau, has been spewing ash and lava for months. Sixty-four hectares (0.64 square kilometres) of the southwest side of the volcano collapsed.
“This caused an underwater landslide and eventually caused the tsunami,” said Dwikorita Karnawati, head of the meteorological agency.
Aid trickled in to Pandeglang, the worst-affected area on Java’s West Coast, and hundreds of soldiers and volunteers picked through piles of wreckage looking for bodies along a 100 kilometres stretch of beach.
The vast archipelago, which sits on the Pacific “Ring of Fire”, has suffered its worst annual death toll from disasters in more than a decade. Earthquakes flattened parts of the tourist island of Lombok in July and August, and a double quake-and-tsunami killed more than 2,000 people on Sulawesi island in September.
Saturday’s tsunami came with almost no warning and destroyed more than 700 buildings, from small shops and houses to villas and hotels.
Disaster mitigation agency spokesman Sutopo Purwo Nugroho said Indonesia had no warning system for volcanoes and underwater landslides.
President Joko Widodo visited the area on Monday and said an alert system was needed.
“I’ve instructed the Meteorology, Climatology, and Geophysical Agency to buy a detection device or a system that would provide an early warning so that the residents can be spared,” he told reporters.
Several scientists said earlier the most likely cause of the tsunami was the collapse of part of the volcano.
Families continued to stream out of the area on Monday for fear of further tsunamis, jamming roads already blocked by debris.
Britain, Australia and Canada advised nationals to monitor the situation closely and the United States embassy said it was ready to assist if needed.
The timing of the tsunami over the Christmas season evoked memories of the Indian Ocean tsunami triggered by an earthquake on December 26, 2004, which killed 226,000 people in 14 countries, including more than 120,000 in Indonesia.
Witnesses recalled how a light breeze was followed by a huge wave that smashed together wooden fishing boats moored off the coast.
Dented vehicles were shunted together by a wave that carried chunks of metal, felled trees and left roof tiles, wooden beams and household items strewn across roads. Some cars ended up in rice fields.
Nurjana, 20, ran for half an hour to the mountains after the tsunami hit. Her beachside stall, where she sold snacks to tourists, was washed away.
“I opened the door straight away and saved myself. I jumped over the wall,” she told Reuters.
“Everything is destroyed.” Heavy equipment was being used to help with rescue efforts.
Medics were sent in with the military, while groups of police and soldiers reached remote areas.
One team of volunteers who worked on disasters in Lombok and Palu was looking for victims at Villa Stephanie, one of dozens of beachside retreats, where eight people were missing.
“It’s difficult here because it’s piled with debris,” said West Jakarta Tagana chairman Muhammad Idris, who led the team.
“This year has been pretty busy. The disasters have been more severe,” he said.
At least five bodies were found in that area on Monday.
Military and other rescuers used an excavator to remove cars and debris, including piles of steel roofing tangled like spaghetti.
The western coast of Banten province in Java, Indonesia’s most populated island, was also badly hit and at least 60 people were killed in Lampung in southern Sumatra, the disaster agency said.
Authorities buried 16 bodies in a mass grave in South Lampung late on Sunday at the request of relatives, Colonel Erwin Djatmiko, a military commander there, told Reuters.
Television footage showed how the tsunami washed away an outdoor stage where Indonesian rock band Seventeen was performing for hundreds of guests at a party for utility company Perusahaan Listrik Negara (PLN).
At least four band members and support crew were killed, lead singer Riefian “Ifan” Fajarsyah told followers in a tearful Instagram account. The band’s drummer was among the missing.
Another 29 PLN employees and relatives were also killed.
Anak Krakatau erupted again just after 9pm on Saturday and the tsunami struck 24 minutes later. Earthquake geologist Ben van der Pluijm said an underwater landslide would be “like suddenly dropping a bag of sand in a tub filled with water”.
The eruption of Krakatau in 1883 killed more than 36,000 people in a series of tsunamis. Anak Krakatau is the island that emerged from the area in 1927 and has been growing ever since.