Many others are feared trapped under the debris of the under construction milling house of army-run Mongla Cement Factory in Bagerhat.
The roof of the building crumbled in a heap at around 1pm on Thursday.
The government has launched an investigation.
Fire Service’s Bagerhat Station in-charge Jainal Abedin said from the scene that they found six bodies until midnight.
Deputy Director Mizanur Rahman said they feared over 50 construction workers were trapped ‘alive or dead’ under the debris while more than 50 others were injured.
Bagerhat Deputy Commissioner Jahangir Alam said over 100 workers started to build the roof of the milling house, which was as high as a four-storey building, in the morning.
“The roof collapsed sometime between 1pm and 1:30pm. Many workers were trapped under centring pipes, rods and casting materials,” he added.
He also said the fifth body was found in the evening.
The rescue operation ran into the night under additional lights.
Mongla Cement Factory, established by the Sena Kalyan Sangstha (armed forces welfare association) beside the river Pashur in 1994, makes Elephant Brand cement.
The committee members include two members of police from Khulna Range including a deputy inspector general and Public Works Department’s chief overseer of Khulna Division and executive engineer.
A representative of Sena Kalyan Sangstha, Khulna Fire Service’s deputy director, Khulna Local Government Division’s deputy director and a representative of Coast Guard are also on the committee.
Earlier, Mongla police’s Assistant Sub-Inspector (ASI) Uttam Chatterjee said around a hundred workers were wounded in the accident.
Navy, Coastguards and fire service launched rescue operation immediately after the accident.
The bodies of four workers were sent to the Mongla Port Hospital.
Doctor Prakash Chandra Mandal identified three of them as Maharuf Hawlader, Amir Akandi and Al Amin.
He said four of the bodies were kept in his hospital.
The number of injured workers admitted to the hospital was nine, he said.
Statement of the armed forces
The military’s press wing said China-based CNBM International Engineering Limited was directly supervising the work to extend the cement factory.