According to
Finnish YLE News the air traffic controllers authorized a Nordic Regional Airlines) ATR 72-500 plane with 60 pax to takeoff while a snowplough and two tractors were clearing snow from its runway.
The incident took place at around 9:30 on Tuesday morning (January 23rd). The Safety Investigation Authority is investigating the incident as a serious risk situation and the authority's director said the fact that a collision did not take place was mostly down to simple luck.