It’s actually hard to tell in many of the photos if the damage was caused by the rapidly advancing storm surge (almost like a tsunami) or by the high winds. In both cases, pretty much everything is knocked flat and piled a meter or so high.
One of the witnesses said the water was as high as a tall coconut tree. And, reading that article, people drowned because the water was so strong, they had no control of where the water sent them. A fella who was in the water said people were washed away and he couldn’t do anything about it because he was trying to save himself.
So, it was a combination of drowning or getting killed by falling debris. I’ve looked at a lot of pictures of those scenes and bodies are in the streets under debris and you know those living people were hunkered down somewhere and not in the streets.