Police of the district on Wednesday said several people relevant to the case have been summoned for questioning.
Measures have been taken to prevent the images and footage recorded by these cameras from being leaked.
Previously on June 30, a 24-year-old woman discovered that hidden cameras were embedded behind the electric sockets in her apartment's bathroom.
When the women inspected the devices, they were already plugged in and operational.
The women said they have rented the place for the past six months.
Recently, hidden cameras were also found in an apartment in Hanoi's Ha Dong District, and the owner of the apartment was fined VND12.5 million ($491) for installing them.