JAKARTA, Indonesia – The tsunami that swept thousands of inhabitants in Java and Sumatra on Saturday was caused by the eruption of active volcano Anak Krakatau.

A day after the deadly wave, the volcano erupted and shot fiery ash on Sunday.

According to National Disaster Management Agency spokesperson Sutopo Purwo, Anak Krakatau has already been exhibiting some activity in the past few months which is why the residents were advised to stay away from the volcano area.

This in itself was already a warning of a possible tsunami.

Sutopo explained though, that there still is no tsunami warning system which is why they couldn’t pinpoint when the tsunami might have occured. This was due to the lack of funds and technical problems with regards to their system. Because of that, they haven’t been able to advance their system since the year 2012.

The deadly tsunami struck at 14:30 GMT and claimed 373 lives while injuring over 1,400 people.

Another 128 people are still missing.