More deadly tsunamis could strike the Indonesian coastline in the coming days, authorities warn, as the volcano which triggered the weekend's devastating wave continues to erupt.
At least 373 people have died from the tsunami, which struck the Indonesian coastline without warning Saturday night. Hundreds more are injured and more than two dozen remain missing.
In the wake of Saturday's disaster, Indonesian President Joko Widodo ordered Indonesia's Meteorology, Climatology and Geological Agency (BMKG) to purchase detectors which would provide "early warnings to community."
Eyewitnesses described fleeing for their lives as beachfront homes were swept away in the wave, which is thought to have been caused by underwater landslides following the eruption of the Anak Krakatau volcano.
According to local media, the wave reached as high as three meters (10 feet).
Sutopo Purwo Nugroho, a spokesman at Indonesia's National Disaster Mitigation Agency, warned Sunday that more tsunamis were possible as long as the volcano remained active.
"We are cautioning the people to remain cautious," Sutopo said. "Agencies are still continuing to analyze the root cause ... the Krakatau volcano continues to erupt, which could potentially trigger another tsunami."
Adding weight to his warnings, Sutopo raised the issue of Indonesia's outdated tsunami buoy network which he said hasn't worked properly since 2012.
"Vandalism, limited budget, technical damage caused no tsunami (alerts) at this time," he said on his official Twitter account.
A lack of warning was also blamed for the high death toll in Indonesia's October tsunami which killed more than 2,000 people on the western coast of Sulawesi.
Taken by surprise
A crowd was watching Indonesian pop band Seventeen at a show organized by state-run electric company PLN at the Tanjung Lesun beach resort when the massive wave crashed through the stage and threw it into the audience.
In a series of emotional messages posted on Instagram, lead singer Riefian Fajarsyah said that his three band members and Seventeen's manager, had died.
Fajarsyah's wife, Dylan, is still missing.
"I am still here - I am not going anywhere - I will pick you and we can come home together sweet heart," Fajarsyah said.
According to Indonesia's National Disaster Mitigation Agency, 1459 people were injured and 128 people are missing, according to Indonesia's National Disaster Mitigation Agency. 5665 people have been displaced.
According to 843 people were injured and another 28 are unaccounted for.
Daniel von Rège, head of mission in Indonesia for Doctors without Borders, said more bodies and injured people were expected to arrive at hospitals across the region over the coming days.
At least 558 houses were destroyed, while nine hotels, 60 restaurants and 350 boats were heavily damaged, an indication of the tsunami's impact on residential and tourist areas.
No foreigners had been reported killed or injured.
Indonesian President Joko Widodo headed to the disaster zone on Monday morning, saying on his official Twitter he was praying for the victims of the tsunami.
Tsunami caused by underwater landslides
Indonesia's Ministry of Maritime Affairs confirmed on Monday that the tsunami had been triggered when the Anak Krakatau volcano erupted in the Sunda Strait between the islands of Java and Sumatra, prompting a series of underwater landslides.
"Sixty-four hectares of the slope collapsed ... Our censors did not sound early warning because they are for tectonic activity not volcanic activity," spokesman Rahmat Djamaluddin said.
When the displaced rock shifted beneath the water's surface, it "pushed up" the water on top of it, CNN meteorologist Allison Chinchar said, and generated the tsunami.
Anak Krakatau sits between the islands of Java and Sumatra.
The tsunami's impacts were compounded by a tidal wave caused by the full moon, BMKG said in a news release.
Anak Krakatau is known for its 1883 eruption -- one of the deadliest in recorded history -- that killed more than 36,000 people.
Despite the devastating 2004 Boxing Day tsunami that killed hundreds of thousands of people, Indonesia lacks proper equipment to warn of an incoming tsunami threat.
"We need a multi-hazard early warning system," said Nugroho. "And we need lots of it."
Nugroho pointed out tsunamis are faster and less predictable than tidal waves, which are caused by atmospheric conditions.
"We used to know that a tsunami happens after an earthquake. There was no quake last night," he said, referring to the sub-aquatic landslides. "That is why there was no warning."
Prayers pour in from around the world
Pope Francis prayed for the tsunami victims at his regular Sunday Angelus service in St. Peter's Square.
"I am spiritually close to the displaced and to all the people affected, imploring God for relief in their suffering," he said. "My appeal is that these brothers and sisters may not lack our solidarity and the support of the international community."
US President Donald Trump addressed the "unthinkable devastation" on Twitter Sunday morning. "We are praying for recovery and healing," Trump wrote. "America is with you!"
The International Federation of Red Cross and Red Crescent Societies in Indonesia expects the death toll to rise, spokeswoman Kathy Mueller said. It's providing support by bringing in basic household items, clean water and equipment to clear debris.
The UN World Food Programme also stood ready to support the Indonesian government, according to WFP spokeswoman Bettina Luescher.