The death toll from a tsunami on the Indonesian island of Java and Sumatra jumped to at least 373, as rescue workers stepped up efforts to reach many areas swept away by the deadly waves.

The tsunami hit the Indonesian strait on Saturday almost without warning in the darkness, smashing into houses, hotels and other buildings.

According to Rob McBride of Aljazeera, support from the Indonesian government and non-governmental agencies (NGOs) trickled in to Pandeglang, the worst-affected area on Java’s west coast, as Indonesian President Joko Widodo expressed his sympathy and ordered government agencies to respond quickly to the disaster.

But many survivors are concerned about the inability of the disaster management authorities to predict the devastating waves.