A 24-year-old woman sustained serious injuries when the train collided with a backhoe on the stretch of track from Norrköping to Linköping. The woman underwent an emergency operation during the night.
A further 17 people suffered minor injuries in the collision, including the 22-year-old backhoe driver who is recovering in hospital and will be moved from intensive care on Monday.
The backhoe was performing track work on the embankment when the vehicle moved too close to the railway tracks.
The rear bucket ripped along the side of the train with the locomotive's momentum spinning the backhoe which collided several times with the sides of the carriages, smashing windows and tearing at the metal façade.
Due to the ongoing maintenance work only one of the railway tracks was open and a speed limit of 70 kilometres/hour had been imposed on the stretch. This limit may have been exceeded, according to new information which came to light on Monday morning.
"The emergency services have informed us that the train had a speed of around 100 kilometres per hour, but the investigation will have to establish if this is true," said police spokesperson Mikael Skoog.
The Swedish Accident Investigation Board (Statens haverikommission - SHK) announced on Monday morning that it had launched an investigation into the accident.
"We have two members of staff at the scene and they are conducting an initial preliminary investigation. They expect to complete their work on Monday. We can not yet say anything about the cause of the accident," said Karin Hellner at SHK to news agency TT.
The Swedish Transport Administration (Trafikverket) is conducting its own investigation into the accident which occurred shortly before 8pm.
The train had 244 people onboard when it collided with the backhoe. The train had departed from Stockholm at 5.40pm and was due to arrive in Malmö shortly after ten.