On Tuesday morning a fire on a construction site caused a threatening situation in Helsinki's downtown Katajanokka district. The rock deep in a tunnel were excavating a group of 22 workers, when rubber mats - used in rock blasting to stop debris from flying around - caught fire. No one was injured in the fire, the workers managed to escape. A wide area police cordoned off and residents were advised to keep doors and windows closed as acrid smoke drifted across the city center. The adjacent headquarters of Stora Enso even though acrid smoke spread into the surrounding area was no need to evacuate its employees. Evidently, by a failure in the heating system of the construction site was caused the fire.