The district records 40.8 degrees Celsius, the highest this seasons
The incident took place at the Upazila's Bhatiapara intersection around 11am on Monday, said Azizur Rahman, chief of Kashiani Police Station.
Police could not immediately confirm the identity of the victims.
“A local bus was heading to Deshpur from Gopalganj,” said Atiar Rahman, chief of Bhanga Highway Police Station.
On the way, the driver lost control of the bus and struck a parked truck, leaving three people dead on the spot and another victim died at the Kashiani Upazila Health Complex, he said.