No injuries to residents were reported, and an evacuation was not needed.

Firefighters later found the carcasses of 40 cats in cages.

But Ivy Tse, a director of animal charity group House of Joy and Mercy, said its volunteers had combed the incident site and recovered 71 carcasses.

Tse said it was uncertain if there were additional ones.

She added that the landlord of the premises said that a friend had been using the site to house cats.

Investigations suggested the fire was caused by a short circuit in the air-conditioning system and no flammable materials were found at the scene, the department added.

The Society for the Prevention of Cruelty to Animals (SPCA) said it had been contacted by authorities.

“But since all cats were declared dead on site, police were looking for their owner to handle the carcasses. Our inspectors did not go to the site,” an SPCA spokesman said.

The premises had once been used as a dog playground called “So Ka Chon”. Its Facebook page showed the venue had hosted activities in 2022, while a Google search indicated it had permanently closed.

The Post has contacted “So Ka Chon” for comment.

Nearby residents reportedly said the house had frequently been visited by individuals whom they believed to be employees of a pet hospice company. Numerous urns containing ashes, incense money and photographs of cats and dogs were found among the debris, they said.

The owner of the house, who had been there on Sunday night, said a number of the cats were strays and had been cared for on the premises, according to a source. She had left at about 11pm, after making sure the air conditioning was turned on and that pet food had been left out for the cats.

She had reportedly planned to return to the site at noon but was unexpectedly notified by police about the fire.

Steven Ho Chun-yin, a lawmaker for the agriculture and fisheries sector, said the breeding and sale of pets were regulated by the law, but it remained challenging to deter well-intentioned but ill-equipped animal enthusiasts.

“Some animal-lovers may think they can manage to take good care of many at a time, but it is hard to know for sure,” Ho said.

“If residents have a reasonable suspicion that an animal is being mistreated, such as being neglected or living in cramped conditions, they should report it to the authorities.”

He added that reporting it early could get authorities, such as the Agriculture, Fisheries and Conservation Department, involved to identify high-risk cases and prevent similar tragedies from happening.

Under the Prevention of Cruelty to Animals Ordinance, it is illegal for anyone to engage in any act that causes unnecessary suffering to any animal, without reasonable cause.

Offenders face a maximum penalty of three years in jail and a HK$200,000 (US$25,600) fine.

Additional reporting by Danny Mok