The deceased has been identified as Singmehnla Marma, 18.
Those missing are the Upazila's postmaster Rabiul, 50, health worker Munni Barua, 30, Krishi Bank’s Second Officer Gautam Nandi and Mesing Marma, 15.
Four others, who were trapped in mud after the landslide, have been rescued alive.
The incident took place on Sunday morning at Ruma Upazila’s Dalianpara area in the hill district.
Three of the four people rescued so far have also been identified as NGO worker Ongkhwai Marma, 26, Upazila Primary Education Officer Belal Hossain, 48, Minjhini Para Government Primary School’s Headmaster Ranjan Tanchangya, 48.
All of them were admitted to Bandarban Sadar Hospital afterwards, said Ruma Upazila Chairman Ongthwaiching Marma.
The Bandarban-Ruma Road was blocked until Sunday afternoon, and the rescue operation was still on to find the missing four, UNO Haque said.
"But, 12 passengers of the bus then started walking to cross the area. Four or five of them had managed to cross first, but suddenly a second landslide struck, burying the others," said the Upazila administration chief.
Bandarban Fire Service official Iqbal Hossain said teams from the local army and BGB camps, fire-fighters and police had managed to rescue four people alive.
Rescue efforts will continue until the missing people are found, he added.