Automatic Alarm turned into smoke in a building. A fire in an oven produced heavy smoke in a commercial structure. This was because the business was not using their kitchen exhaust fan. The first-in crew forced entry into the rear of the building to mitigate the situation by shutting down the oven fire and used positive pressure fans. Two engines and one truck where dispatched. *This was the second call in the District. The other call was the woods fire .