A South Korean man tending a family grave is suspected of sparking one of the ‘unprecedented’ wildfires that ravaged the southeastern part of the country last week, the National Police Agency said Monday.

South Korean firefighters were able to fully contain the wildfires that have ravaged the southeastern part of the country and left 30 dead, officials said, while authorities began a joint investigation into the cause.

The death toll included a pilot who died after a helicopter crashed during efforts to contain wildfires in the southeastern town of Uiseong, one of the areas hardest-hit.