Explosion rocks Quaker Oats factory in Iowa, all employees safely accounted for

article (Cedar Rapids Fire Department) The Brief An apparent explosion and fire struck the world's largest oat mill in downtown Cedar Rapids, Iowa, Saturday.Mayor Tiffany O'Donnell confirmed that all workers are safe and accounted for.Officials are currently investigating the cause of both the explosion and fire. An apparent explosion and fire at the world's largest oat mill in Iowa sent thick black smoke billowing over downtown Cedar Rapids Saturday. What we know: The Cedar Rapids Fire Department says it happened at 4:44 p.m. local time and when first responders arrived they found heavy smoke and flames coming from the north side of the building.  (Cedar Rapids Fire Department) Additional fire crews from Marion, Hiawatha and Linn County were called in to help battle the blaze, which was extinguished around 6:25 p.m. What they're saying: Cedar Rapids Mayor Tiffany O'Donnell said in a Facebook video that all workers were safe and accounted for.  "It's not heavily populated with employees and team members. Which, of course, in this case was a blessing," O'Donnell said. By the numbers: According to the company's website, the plant is the world's largest milling facility, processing more than 2 million pounds of oats each day. What we don't know: The cause of the fire and explosion are under investigation. The Source: This article includes information from the Cedar Rapids Fire Department, Cedar Rapids Mayor Tiffany O'Donnell, and FOX Business. This story was reported from Orlando.   U.S.