The accident occurred around 6:00am on the highway near the Boishamura area when four brick kiln workers were on their way to their plant in the auto, said Md Shahjalala Alam, officer-in-charge of Shahbajpur bus stand highway police station.
The three were killed on the spot immediately after the head-on collision between the auto and the truck coming from the opposite direction, the OC said.
A probe has been ordered into the accident, he added.