Firefighters took eight hours to put out a blaze in a 51-year-old industrial building in Kowloon’s San Po Kong on Thursday.

A man in a unit on the second floor of Kai Tak Factory at King Fuk Street spotted smoke coming out from a room at 12:15pm, Ta Kung Pao reported.

He opened the door and found an air purifier inside the room on fire. He escaped with a female colleague, aged 26, who was later sent to hospital after inhaling smoke.

Thick smoke and flames were seen coming out of a window and some loud bangs were heard during the blaze. At 1.30pm the No-3 alarm fire was heard.

The blaze led to 700 students and teachers being evacuated from the nearby Cognitio College.

The building had no automatic sprinkler system – as it was built in 1966, seven years before fire safety requirements were imposed on all buildings in the city, Apple Daily reported.

Over 300 fire engineers and firemen were deployed to the scene. But the blaze was not extinguished until 8pm, am730 reported.

Owners of nearby restaurants sent food and drinks to the firemen in a show of thanks for their efforts and hard work to put out the fire.