Tributes have been pouring in for the victims of this week's devastating fire at Wang Fuk Court in Tai Po, as Hong Kong on Saturday entered three days of mourning.

Books of condolence have been set up in the SAR's 18 districts.

The Fu Heng Neighbourhood Community Centre, some two kilometres from the site of the blaze that killed at least 128 people, saw a number of people who went to pay their respects.

"I have written two lines that read: 'Deeply mourning the victims of the fire at Wang Fuk Court. May residents of Wang Fuk Court be able to move beyond their grief as soon as possible," said one woman, named Chung.

Another said she was left devastated by the news of the blaze.

"I can't imagine how things have unfolded... I can't do much, all I can do is pray," she said.

Meanwhile, police have begun operations at Wang Fuk Court.

About 600 officers from the disaster victim identification unit, clad in blue helmets and white overalls, were deployed to the scene in the morning, the force said.

At least four coaches took the group to Tai Po.

Officers were then given a briefing before entering the estate.

Earlier, Chief Executive John Lee led government and senior mainland officials in three minutes of silence at the Central Government Offices in Admiralty to pay tribute to the victims.