Authorities say four more bodies have been found near the summit of a Japanese volcano that erupted last weekend, raising the death toll to 51.

Nagano prefecture said in a statement that more than 900 rescue workers resumed searching the slopes Saturday after rain had halted their activity the day before.

The four bodies were near the ash-covered summit area of Mount Ontake. Many hikers had been resting at the summit area or having lunch during the surprise eruption a week ago. It was not immediately known if the four were among the 16 that authorities said are believed still missing.

Authorities have said most of those who died were hit by boulders or rocks.