More deaths were feared even as the death toll in a deadly tsunami that hit two provinces on either side of the Sunda Strait on Saturday night crossed 222, with hundreds of others injured.
A tsunami warning buoy system set up in the strait by the Indonesian government in 2008 gave no warning as it has not been working since 2012, said Dr Sutopo Purwo Nugroho, spokesman for Indonesia's National Disaster Management Agency (BNPB).
"So, nobody knew when the tsunami was occurring in the Sunda Strait. We only knew (when) it struck the beach," he told The Straits Times.
All of the dead and injured were Indonesians, and many were holiday-goers in hotels and bungalows, according to BNPB.
"These figures may rise further because not all victims have been evacuated, not all health centres have filed their reports and not all locations have had their data fully reported," said Dr Sutopo.
The tsunami hit locations in Banten province, on the western tip of Java, and Lampung province, in southernmost Sumatra.
The 2m-to 3m-high waves struck at night, causing severe damage to at least 556 houses, nine hotels, 60 food outlets and 350 boats and vessels. Rescuers have found the most number of victims at the Hotel Mutiara Carita Cottage on the Carita beach in Banten province, Hotel Tanjung Lesung in Lampung province, and Banten's coastal village of Sambolo, located in the worst-affected Pandeglang district.
A tsunami triggered by volcanic eruption, not a common occurrence in Indonesia, cannot be detected by the existing early warning system for tsunamis triggered by earthquakes, according to Indonesia's Meteorology, Climatology and Geophysics Agency.
President Joko Widodo said he has "ordered all relevant government agencies to immediately take emergency response steps, find victims and care for the injured".
Yesterday, President Halimah Yacob and Prime Minister Lee Hsien Loong wrote to Mr Joko to convey their condolences over the deadly tsunami.
Indonesian officials hope the damage may not be as extensive as feared. Indonesia's armed forces chief Hadi Tjahjanto said an aerial view of the affected areas showed downed trees only as far as 200m to 250m from the beach in both provinces. "Roads are mostly accessible, no bridge has collapsed," he said on national TV.
Based on a preliminary assessment to be confirmed, the tsunami was caused by an undersea landslide resulting from volcanic activity on Anak Krakatau, and was exacerbated by an abnormally high tide because of the current full moon, according to BNPB's Dr Sutopo.
Mr Rudi Suhendar, the head of Indonesia's Geological Agency, told The Straits Times he still could not rule out that weather, rather than an eruption, had caused the tidal surge, as the volcano had been active since the end of June and the amplitude of Saturday's eruption was not the biggest.
Anak Krakatau, or Child of Krakatau, is a volcanic island in the Sunda Strait formed from the eruptions of the Krakatau volcano.
Anak Krakatau was among the 20 volcanoes in Indonesia listed by the government as alert zones for travellers, the Jakarta Post reported last Thursday. Other volcanoes on the list include Mount Sinabung in North Sumatra and Mount Soputan in North Sulawesi.
Indonesia, the world's largest archipelagic nation with more than 17,000 islands, lies in the Pacific Ring of Fire, a region of frequent earthquakes and volcanic eruptions as a result of tectonic plate movements.
On Sept 28, a quake and tsunami killed more than 2,000 people in the city of Palu and Donggala regency in Central Sulawesi province. Tsunami warning sensors also failed in that disaster.
In 2004, a tsunami triggered by a magnitude-9.3 undersea earthquake off the coast of Sumatra killed 220,000 people in countries around the Indian Ocean, including 168,000 in Indonesia.
•Additional reporting by Linda Yulisman