Authorities are investigating the cause of a blaze at a Sau Mau Ping home early on Friday that took firefighters more than eight hours to extinguish, though no one was harmed.

The Fire Services Department said the fire at 9 Anderson Road, quickly spread and intensified after breaking out at around 12.30am on Friday morning.

Just over an hour later, the blaze was upgraded to No.3 alarm.

Drones equipped with thermal imaging cameras were sent in to help the control centre assess the situation, and four teams of firefighters used four jets to combat the blaze, largely extinguishing it by 8.40am.

Senior Division Officer Chan Fu-shan said it was a difficult operation.

“[It was difficult] mostly because it was an very large unit measuring 30 by 30 metres, spread over two stories. Add to that the intense heat and smoke generated by the fire, and it made it difficult to push forward.”

He added that the fire had spread quickly due to the layout of the house, and the amount of things stored inside.

All 18 people made it out of the residence without assistance, and no one was hurt.