Po Hing Fong belongs to one of the earliest development project areas in Hong Kong. 
As with most our haunted spots, bad things soon occurred in this one too.
Plague broke out in Hong Kong and thousands of people succumbed to the gnarly illness. Hong Kong colonial government, in order to contain the contagion, had all patients sent to the isolated area which is now known as Po Hing Fong.

After the plague subsided, and all isolated victims perished in great suffering, surrounding buildings had to be burned down and rebuilt.

It is often said that trouble doesn't come alone, however, and following the events related to the plague, when WWII broke out, Po Hing Fong was added to the list of locations used for massive scale torture and murder. 
Because of this, the area is said to be full of lingering souls and many strange happenings took place there.
The most famous incident was reported back in 1949, where residents heard a sudden commotion outside and woke up just to see hundreds of refugees running for their lives just to disappear in the fog minutes later.
The next day everyone compared their notes on this event and agreed what they saw the night before was too strange to be considered a mere coincidence.