The two buildings are located side by side in front of Bangladesh University of Business and Technology, according to local media reports.
"Twelve bodies were brought to the Dhaka Medical College Hospital and the National Institute of Burn and Plastic Surgery in Dhaka," Talha Bin Jashim, officer-in-charge of the media cell of the Fire Service headquarters in Dhaka, told Xinhua.
At least 12 firefighting units rushed to the spot to douse the fire at around 11:40 a.m. Tuesday.
According to the official, the blaze in the seven-story garment factory started on the third floor and has been largely extinguished.
However, he said firefighters were still working to fully contain the fire at the chemical warehouse, which stored hazardous materials, including bleaching powder, plastic, and hydrogen peroxide.
The death toll in the blaze is likely to rise, warned another fire official, who did not want to be named.
The cause of the fire has not been ascertained, as the security officials have yet to comment on the incident.