The fire broke out at Bikon Knitwears in Salna area around 9am on Monday, said Md Rafiq Uddin, senior executive of Joydebpur Fire Service.
"Panic spread among the workers as smoke started billowing out. They doused the flames before fire fighting units reached there," he told bdnews24.com.
The officer said electric short-circuit had caused the fire.
The fire broke out on the first floor, they said.
The injured workers were admitted to Shaheed Tajuddin Ahmad Medical College and Hospital in Gazipur.
Residential medical officer Pronoy Bhushan Das said 55 workers were brought to the hospital until 11am.
"They fell sick due to panic and also suffered cuts and bruises. Seven of them have been sent to Dhaka Medical College Hospital for medical tests while the rest were released after first aid,"he said.