It was at 10.30 that the alarm was received about an accident on the E20 at the height of the Barvalapp.
According to the rescue service, it is very slippery on the spot and one of the cars drove into the center railing.
The other car tried to dodge and ended up first in the side railing and then collided with the first car.
One person is said to have been taken to hospital in connection with the accident.
Traffic has been closed in the direction from Eskilstuna to Strängnäs.