At least 20 people have been killed and 165 injured after a tsunami hit the coast around Indonesia’s Sunda Strait, government officials say.
The country’s disaster management agency says two people are missing, and dozens of buildings were damaged.
It says the possible cause of the tsunami were undersea landslides after the Krakatoa volcano erupted.
The Sunda Strait between the islands of Java and Sumatra connects the Java Sea to the Indian Ocean.
The deaths were reported in the Pandeglang, South Lampung and Serang regions.
Officials warn that the death toll is likely to rise further. The disaster management agency said high seas as a result of the full moon may also have contributed to the strength of the wave.
Eyewitness Oystein Lund Andersen, who was on the beach at the time, told the BBC two waves had hit, with the second much bigger than the first.
Mr Andersen, a Norwegian professional volcano photographer, said he had rushed to the hotel where his family were staying, and they later went to a higher ground in a forest.
He added that there had been heavy eruption sound prior to the tsunami.
Footage posted by the head of disaster agency showed the aftermath of the tsunami, with flooded streets and an overturned car.
Data sementara dampak tsunami di Pantai di Kab Pandeglang, Serang dan Lampung Selatan hingga 23/12/2018 pukul 04.30 WIB: tercatat 20 orang meninggal dunia, 165 orang luka-luka, 2 orang hilang dan puluhan bangunan rusak. Data korban kemungkinan masih akan terus bertambah.
He had earlier posted footage of water rushing in and local residents trying to flee in panic.
Emergency officials are now investigating whether the tsunami was caused by Anak Krakatoa, a volcanic island in the Sunda Strait.
In September, more than 2,000 people died when a powerful earthquake struck just off the central Indonesian island of Sulawesi, setting off a tsunami that engulfed the coastal city of Palu.
On 26 December 2004, a series of huge waves triggered by a powerful earthquake in the Indian Ocean killed about 228,000 people in 14 countries, including Indonesia.
Indonesia is prone to earthquakes because it lies on the Ring of Fire – the line of frequent quakes and volcanic eruptions that circles virtually the entire Pacific rim.
The Anak Krakatoa (Child of Krakatoa) volcano has seen increased activity in recent months.
Indonesia’s geologic agency said that the volcano erupted for two minutes and 12 seconds on Friday, creating an ash cloud that rose 400 metres (1,300ft) above the mountain.
It recommended that no-one be allowed within two kilometres of the crater.
Image copyrightGALLO IMAGES/ORBITAL HORIZON/COPERNICUS SENTINImage captionA satellite image of Anak Krakatoa erupting in August