One received only light injuries.
There were 50 people on the buses, rescue services said.
The accident occurred when two buses stopped at the Espoo Ikea stop on Highway 1. Passengers transferring to the airport were moving to the bus heading toward Turku. A third bus drove into the stop but could not stop due to the slippery road surface and collided with the back of one of the parked buses at 60 km/h.
The scene was covered with a thick layer of smooth ice.
“The road has apparently been salted, but not this stop,” said the on-duty fire chief, Jaakko Niskala.
The police are investigating the case as endangerment of road safety.
