An unidentified boy succumbed to his injuries as an iron rod from an under-construction expressway fell on him and impaled the back of his head.
The incident took place near the British American Tobacco Bangladesh office in Dhaka's Mohakhali area at around 10am on Monday.
One passerby, Abdul Quader Emon, rescued the boy from the spot and took him to Dhaka Medical College Hospital.
He died while undergoing treatment at the emergency department of the hospital, said Inspector Bachchu Mia, in-charge of the DMCH police outpost.
The boy was believed to be a 12-year-old.