Final answer:
The cell block that burnt down was originally used as a Colored-Orphan Asylum before it was destroyed by a mob-set fire. The fate of the 300 orphaned children housed in the asylum is uncertain.
Step-by-step explanation:
The cell block that burnt down was originally used as a Colored-Orphan Asylum in 5th Avenue. The structure was set on fire by a mob, resulting in its destruction. It is unclear what happened to the 300 orphaned children housed in the asylum at the time. It is speculated that they were given some warning and were able to escape before the fire.