Firefighters were called back to the site of a grain elevator explosion in Union Mills last night after a hot spot apparently rekindled. Smoke was spotted billowing from the silo at the Union Mills Co-Op around 8 last night. It exploded around 1:30 Monday afternoon, killing 67-year-old James Swank, who lived nearby. He was on top of the silo at the time, according to the LaPorte County coroner, who says he fell to his death. Federal, state and local investigators are still trying to determine the ignition source of the blast. That has proved challenging, as the structure is not yet safe for them to enter. Early indications are that the explosion took place near the top of the 175 foot tall structure.