A five-storey building has collapsed in the Bangladeshi capital, Dhaka, leaving at least 15 dead and 50 injured.
Soldiers have been brought in to help police and firefighters search for anyone still trapped. Locals say 200 people may have been in the building.
Officials say the building caved in as renovation work was being carried out.
It comes only two days after a fire swept through a textile mill in the south-eastern port city of Chittagong, killing more than 50 people.
Last April, more than 60 people died when an illegally-constructed garment factory collapsed near Dhaka.
The BBC's Waliur Rahman in Dhaka says the latest building to collapse was being renovated for use as a hospital after a garment factory moved out.
Locals say more than 200 people may have been inside the building when it started to crumble.
Senior army officer Nizam Ahmed, who has been overseeing the rescue operation, told the BBC that he feared many might still be trapped.
Witnesses report seeing the building crumble to the ground
Shahidul Islam told the AFP news agency he had seen the building crumble as he carried back tea for his boss.
"The first two floors of the building were swallowed by the ground which gave way within just a few minutes," he said.
"Some people who were working in the front portion of the building managed to escape before the building collapsed."
Following Thursday's factory fire, garment workers and human rights activists marched through Dhaka to demand better safety in factories and proper compensation for the victims.
The textile industry has been plagued by accidents due to poor safety standards, despite earning Bangladesh some $6bn (£3.4bn) annually.
In 2000, at least 48 workers died when a locked fire exit left them trapped in a burning factory near Dhaka.