Hundreds of buildings were destroyed by the wave, which hit beaches without warning in South Sumatra and the western tip of Java about 9.30 pm local time on Saturday, national disaster agency spokesman Sutopo Purwo Nugroho said in a statement. Authorities say the tsunami may have been triggered by an abnormal tidal surge due to a new moon and an underwater landslide following the eruption of Anak Krakatoa, which forms a small island in the Sunda Strait between Java and Sumatra. Nugroho said that the death toll would likely increase.