Fire service sources on Saturday morning said the fire was extinguished after 2 at night.
Fifteen firefighting units worked to extinguish the blaze, fire service official Mahfuz Riben told Prothom Alo.
He said two firefighters also sustained minor injuries while working to put out the blaze.
Sub inspector Bozlar Rahman on Friday night said they suspect the fire broke out from a gas cylinder blast.
Over 2,000 families live in the slum, he added.