Garment contractors here appeal to merchants because of workers' low wages.
It was not immediately clear which retailers were doing business with the factories.
The last major building collapse in the country occurred in 2005 in the same area and killed more than 70 people, the national news agency said.
A fire at the Tazreen Fashions Factory in another suburb of Dhaka in November killed at least 112 people. Tazreen had made goods for Walmart and Sears, though both companies said they were unaware that the factory had made goods for them.
Garments account for 80% of Bangladesh's $24 billion in exports.
The country has about 4,500 garment factories where workers make clothes for various international brands. It's on track to surpass China within seven years as the world's largest apparel manufacturer.
Scott Nova, executive director of the Worker Rights Consortium, said the pressure to cut prices results in substandard safety conditions.
"The worse the dangers get, the more business comes in, so the government has no incentive to fix anything," he said. "We ask ourselves every day what it's going to take to fix this."