The flames were seen around 10:30pm Thursday. Rescue workers said the rags on the ground from the readymade garment factories caught fire while they were trying to cut iron rods in the wreckage.
Fire-fighters doused the flames in 15 minutes.
The death toll from the worst case of building collapse in the country swelled to 255 while rescuers so far have pulled alive more than 2,000 people.
At least 170 dead bodies have been handed over to the relatives until now, officials from the temporary control room at the Savar Bus Stand, near the collapse site, said at around 9:30pm.
The rescue efforts which began on Wednesday have been going on for more than 33 hours.
The operation will continue until Saturday before the process to remove the wreckage begins, Fire Service and Civil Defence Director Mohammad Zahidul Islam said on Thursday afternoon.
Local residents took out a procession carrying sticks there at around 10pm demanding arrest of the building owner Mohammad Sohel Rana, a local leader of Juba League.