The victims are Md Tanzid, 10, Hedayet Ullah, 7, Asaduzzaman, 12, and ‘Sajib’, 12.
They were admitted to the burns unit at Dhaka Medical College Hospital (DMCH).
The lower storey of a two-storey building at Bhagalpur Lane caught fire around 6pm, said Fire Service Control Room Official Ataur Rahman.
‘Josna’, who works as a cook for a home inside the building, said fire erupted in a room next to the factory when she tried to light the stove.
Tanzid is son to Shah Alam, the owner of ‘Tanzid Leather’ and Hedayet is Josna’s son.
Asaduzzamana and Sajib are child workers from the factory, she said.
Tanzid and Hedayet were in the factory when it caught fire.
Tanzid suffered 15 percent burn, Hedayet 14 percent, Asaduzzaman 5 percent and Sajib 61 percent, said Dr Partha Sankar Pal of the burns unit.