Finland's Safety Investigation Authority said air traffic controllers authorised a passenger plane to approach the takeoff strip while there were three runway maintenance vehicles on it at the time.
The incident took place at around 9:30 on Tuesday morning. According to the authority's director Veli-Pekka Nurmi the vehicles were clearing snow from the runway.
"Both the pilot of the aircraft and the drivers of the vehicles were operating according to directions they'd received. It appears that air traffic control did not have control of the situation at all," Nurmi said.
The vehicles, a snow plough and two tractors, were clearing snow when Norra's (Nordic Regional Airlines) ATR (72-500) was cleared to approach the runway for takeoff, Nurmi said.
"It was very lucky that none of the vehicles were in the plane's path. The Safety Investigation Authority is investigating the incident as a serious risk situation," he said.
Investigation to take months
Nurmi said the fact that a collision did not take place was mostly down to simple luck.
"If one of the vehicles had been in the plane's path the consequences would have been very serious," he said.
It remains unclear where the plane was headed and how many passengers were onboard. Nurmi said that the investigation will begin with speaking to everyone involved in Tuesday's incident.
"We need evidence from the airport and aircraft and then our work will continue," Nurmi said, explaining that the investigation could take about six months before it is complete.
"It is very important to determine how this could have occurred," Nurmi said.
"It is clear that airport's heavy machinery drivers should be certain that no airplanes are on the runway at the same time as they are. And if a plane gets the green light for takeoff the pilot has to know that no vehicles or something else is in the way," he said.
According to news agency STT, Finavia, the nation's airport maintenance and air navigation firm would not comment on whether it has opened its own investigation or not.
Finavia told STT that it is the Safety Investigation Authority's role to inform the public about the incident.