Another 4 were injured in the incident, Pakistan’s ANI reported quoting Pakistan’s ARY News.
The blast on the Peshawar-Quetta Jaffer Express occurred when it was passing the Chichawatni railway station in Pakistan’s Punjab province.
No group has so far claimed responsibility behind the train blast.
The militant group Tehreek-e-Taliban Pakistan (TTP) has been blamed for a majority of recent subversive activities, including attacks on security forces in Pakistan.
It was reportedly behind last month’s suicide attack on a mosque in which more than 100 people, mostly police personnel were killed.
The group, which is believed to be close to Al-Qaeda, has been blamed for several deadly attacks across Pakistan, including an attack on army headquarters in 2009, assaults on military bases, and the 2008 bombing of the Marriott Hotel in Islamabad.