An outpouring of grief swept Hong Kong on Saturday as crowds paid their respects and laid flowers for the 128 people killed in one of the city's deadliest fires, marking the start of an official, three-day mourning period.

A growing number of people arrived at a park near the charred shell of Wang Fuk Court, the residential complex that burned for more than 40 hours, to place white and yellow flowers and handwritten messages of remembrance.

"May your spirits in heaven always keep the joy alive," one of the notes read.

A 69-year-old woman surnamed Wong, who lived in the estate for more than four decades, sat dazed nearby as she counted off a list of deceased neighbours and friends.

"It was a grandmother with a 18-month-old baby... I was very close with them," Wong told AFP, adding that many of the elderly homeowners had a tight bond.

"Yesterday it was confirmed they died."

Elsewhere in the Tai Po neighbourhood, a hall in a community centre was turned into a"condolence point" for the public, one of 18 across the Chinese finance hub.

A man surnamed Ki, 52, was among the dozens who queued to sign the condolence book in silence, which was only broken by sounds of sobbing.

"I can't do anything. I can only hope they rest in peace," he told AFP.

Raymond Tang, who was also in the queue, said his wish was that the deceased can"cross the sea of suffering and depart to the other side".

City leader John Lee and top ministers stood in silence for three minutes at 8:00 am (0000 GMT) outside the government headquarters, where the flags of China and Hong Kong were flown at half-mast.

During the mourning period, celebratory events organised by the government will be axed or postponed, and officials will reduce their non-essential public appearances.

Desperate search

Authorities on Friday afternoon put the death toll at 128 but warned that more charred remains could be found as investigators combed the towers, though they have yet to issue an updated figure.

Legions of police officers from the Disaster Victim Identification Unit, dressed in white full-body protective gear, entered the burnt buildings on Saturday morning, an AFP reporter saw.

Around 200 people were listed as missing and 89 of the recovered bodies had not been identified -- prompting desperate searches at hospitals and victim identification stations.

A man surnamed Fung earlier told AFP he was visiting the housing estate daily to look for his 80-year-old mother-in-law.

"She is on antibiotics... so she is always sleeping. There was no fire alarm, so she might not have known there was a fire," he said.

More than 40 people remained hospitalised on Saturday, with 11 in critical condition, and 21 listed as"serious".

On Friday, the city's anti-corruption watchdog arrested eight people in connection with the blaze, on top of three earlier arrests by police.

Flames had spread quickly through the housing estate in the city's northern Tai Po district on Wednesday afternoon, engulfing seven of the eight high-rises in the densely packed complex.

Authorities said the cause was yet to be determined, but preliminary investigations suggested the fire started on protective netting on the lower floors of one of the towers and that"highly flammable" foam boards, as well as bamboo scaffolding, had contributed to its spread.

Fire services chief Andy Yeung said they discovered that alarm systems in all eight apartment blocks"were malfunctioning", and vowed action against the contractors.

Residents had told AFP they did not hear any fire alarms and went door-to-door to alert neighbours to the danger.

The blaze was Hong Kong's deadliest since 1948, when an explosion followed by a fire killed at least 135 people.

Lethal fires were once a regular scourge in densely populated Hong Kong, especially in poorer neighbourhoods, but improved safety measures have made them far less common.

Security chief Chris Tang said the full investigation into the fire's causes could take up to four weeks.