The incident took place near Bucch railway station in Sher Shah area that overturned four bogies of the Awam Express.
The collision wrecked the engine and power van, and overturned four bogies of Awam Express, an official said.
The incident left at least six people dead and wounded over 150, out of which 10 were said to be in serious condition. Three people trapped inside damaged carriages were also saved, said rescue workers.
A delay was initially observed in response by rescue services due to Eid holidays, according to sources. Relief works were also affected as darkness prevailed in the vicinity.The passenger train was en route to Karachi from Peshawar.