Lasse Petrell, who was caught by the pile-up, told YLE that there were dozens of vehicles both in front and behind his in the chain collision.
"By my count, there are easily 30-40 in front of me, and at least as many behind me and it just goes on. So, yes, that one hundred could easily be true," Petrell told YLE.
Traffic on the highway was at a complete standstill. Including cars that were not involved in collisions, the count of vehicles stranded on the road may be several hundred.
There were no immediate reports of injuries.
Another multi-vehicle collision was also reported on the Lahti motorway near Koivukylä.
