The roof of a five-story cement factory under construction in Bangladesh collapsed Thursday, killing at least four workers and trapping many others.

About 150 workers were on duty when the collapse occurred in Mongla in Bagerhat district, fire official Mizanur Rahman said. At least 40 people were rescued from under the debris and up to 40 others were feared trapped. Many of the survivors were hospitalized with injuries, Rahman said.

Survivors said 50 to 60 people were working on the roof while others were on the ground floor when the collapse occurred, local government administrator M. Jahangir Alam said.

The seaside factory, about 85 miles southwest of Dhaka, is owned by an army welfare organization, the United News of Bangladesh news agency reported. - AP