The mishap occurred near Tando Jam late last night at a crossing near Allah Dino Saand railway station, with four people seriously injured in the incident.
DSP Latif Pirzada said that a van with 15 passengers coming from Matiari to Tando Jam was crushed when it was hit by the Baba Fareed Express going from Karachi to Multan.
"It happened late night and in darkness and there was no one manning the crossing," Pirzada said.
"It became difficult to carry out rescue operations due to the darkness but now bodies have been removed and injured shifted to hospitals while railway traffic has also been restored," he added.