A section of the crater – which emerged at the site of the legendary Krakatoa volcano, whose massive 1883 eruption killed at least 36,000 people – collapsed after an eruption and slid into the ocean, triggering Saturday night’s killer wave.

It struck without warning, washing over popular beaches and inundating tourist hotels and coastal communities, leaving a trail of death and destruction in its wake.

The disaster agency slightly raised the death toll on Wednesday to 430, with 1,495 people injured and another 159 missing. Nearly 22,000 people have been evacuated and are living in shelters.

“There’s a chance the number of fatalities will rise,” agency spokesman Sutopo Purwo Nugroho told a press briefing.

Before the tsunami that killed hundreds, Krakatoa’s massive eruption in 1883 rocked the world

Medical workers have warned that clean water and medicine supplies were running low – stoking fears of a public health crisis – as thousands of displaced survivors cram shelters and hospitals.

Many have been left homeless by the killer wave, and fear going back to their communities.

“I’m here because people said there could another tsunami,” Etin Supriatin said from an evacuation centre in shattered Labuan.

The disaster agency dispatched helicopters to drop supplies into hard-to-reach communities, while hundreds of residents on tiny islands in the Sunda Strait were airlifted or taken by boat to shelters.

“We tried to stay because it’s our island, but after a while we got scared,” said Sariyah, a 45-year-old resident of tiny Sebesi island, who evacuated to the mainland on a boat. “My house has been destroyed so there’s no more reason to stay.”

Sniffer dogs are being used to find those still missing as grief-stricken relatives lined up at identification centres.

But hopes of finding any survivors beneath the rubble have dwindled.

Tubagus Cecep, 63, waited nervously at the area’s main identification centre to see if a body was that of his missing son.

“I’m scared my son is dead, but if I keep my faith in God maybe he could have been swept away somewhere and is still alive,” he said.

At the Tanjung Lesung resort, cars and minibuses had been thrown against buildings, concrete walls cracked into small pieces and trees uprooted. A wooden sign that read “Good Times” lay on the ground.

The tsunami struck the resort as more than 200 workers from the state electricity company were watching pop band “Seventeen” perform.

The four-member group was hurled from the stage as the water slammed into the audience – only the band’s lead vocalist survived.

Another Indonesian tsunami may be imminent, as experts fear extreme weather could collapse Anak Krakatoa volcano

The tsunami was Indonesia’s third major natural disaster in six months, following a series of powerful earthquakes on the island of Lombok in July and August and a quake-tsunami in September that killed around 2,200 people in Palu on Sulawesi island, with thousands more missing and presumed dead.

On Wednesday, thousands prayed for loved ones at mass graves and mosques to mark the 14th anniversary of the 2004 Boxing Day tsunami, which killed some 220,000 people in countries around the Indian Ocean.

Indonesia, a vast Southeast Asian archipelago, is one of the most disaster-hit nations on Earth due to its position straddling the so-called Pacific Ring of Fire, where tectonic plates collide.