At ten o'clock on Wednesday morning, the rescue service is on site with five units just north of Torpasjön's rest area in Kungsbacka municipality.
It must have started with two trucks driving together in a northbound direction on the motorway.
One of them must also have dropped a beam on the road.
Two cars must then have driven into the beam.
Damage situation is unclear.
According to SOS Alarm, no ambulance has been sent initially.
The Swedish Transport Administration estimates that there will be a major impact on traffic until 12 noon.