Four trains are currently stranded at both ends of the Bangabandhu Bridge
The incident occurred on the Dhaka-Chattogram Highway in the city's Paduar Bazar area around 12pm on Sunday, said Mainamati Highway Police OC Alamgir Hossain.
The casualties were identified as Toufique Ahmed Sajal, 26, Kajal Hossain, 28, and Md Shahin, 25.
A Shyamoli Paribahan bus was heading to Chattogram from Dhaka when it rammed a motorcycle moving in the opposite direction, according to the OC.
Police have detained the driver of the Shyamoli Paribahan bus, said OC Alamgir.