They had fled across the border to Bangladesh amid heavy fighting between the Myanmar military and rebel insurgents in Rakhine
The incident took place on the Bagerhat-Mawa Highway at Fakirhat on Friday afternoon killing them on the spot.
Fakirhat police identified four of the victims as Neelkamal Das, 45, and his brother Balram Das, 35, Shyam Das, 30, and Panu Das, 55.
However, the pickup van driver could not be immediately identified.