An explosion and fire tore through a cookie factory in central Greece, killing at least four workers and leaving one person missing, AP reported. The blast struck the Violanta biscuit plant near Trikala during the night shift. The fire that followed severely damaged the factory.

Seven people, including a firefighter, were taken to hospital with injuries. Authorities said none of those hospitalized were in serious condition. Firefighters battled the blaze for hours before recovering four bodies from the wreckage.

AP wrote, police believe the explosion may have started near the factory’s ovens, which run nonstop. All the victims recovered were women. Investigators and emergency crews remain at the site as the cause of the blast is examined