The Volvo they were travelling in was was completely demolished, according to police and the rail operator.
Police describe the dead as young people, although they have not been formally identified and the bodies have been taken to Uppsala for forensic examination, according to Sven Matzols, duty police officer in Dalarna.
In order to establish the identity of the dead, the police will first trace the owner of the car, which is registered to a person in Dalarna. Police suspect no offense in connection with the incident and have not questioned the driver.
"That is done at a later stage," Matzols said.
The fatal accident occurred at an unguarded railway crossing in the southern outskirts of Horndal, between Avesta and Sandviken, according to Håkan Jarl, traffic manager at Tågkompaniet, the company that manages traffic on the line.
The maximum speed at that junction is either 110 or 120 kilometers an hour, and Earl says that the train was at "full speed" at the time of the accident.
The driver, a woman in her 50s, is reported to feel okay under the circumstances. She has received help from a counsellor and will also later meet a doctor, according to Jarl.