At least 150 people are trapped on the roof of Hong Kong’s World Trade Centre after a fire broke out in the building in the bustling commercial district of Causeway Bay.

Police and the fire department said 13 people were injured before firefighters put out the blaze about 4.30pm, local time, on Wednesday.

The cause of the fire is unknown.

Firefighters had been battling the blaze, which had been classified as a level-three incident – with five being the most severe, with two water jets, the government said.

They were using ladders and breathing apparatus in the effort to rescue those trapped.

BREAKING: At least 1,000 people were evacuated from the #HongKong #WorldTradeCentre in #CausewayBay due to a major #fire in the building, and "dozens" remain trapped by the flames, according to police. pic.twitter.com/ay7SjONjQj

— Ifeng News (@IFENG__official) December 15, 2021

Broadcaster RTHK quoted police as saying about 100 people moved from a restaurant to the 39th floor when the fire broke out and smoke filled the dining area.

Seven women and a man were among the eight people taken to hospital, one of them semi-conscious, police said.

The injured are aged between 31 and 72.

BBC reports the fire broke out in the electrical switch room/machine room, which led to the bamboo scaffolding catching fire.

Firefighters received reports about the blaze at the World Trade Center around 12 pm, according to Commercial Radio. The fire, which was raised to the no. 3 alarm by 1 pm, is believed to have broken out on the building's first floor where renovations are going on. pic.twitter.com/NWqNNM6ZRd

— Hong Kong Free Press HKFP (@hkfp) December 15, 2021

The 38-storey building is currently under renovation, with all shops vacated during the refurbishments.

The South China Morning Post reports that only restaurants and offices are in operation.

No fatalities have been reported and rescue operations are still under way.

Outside the building, the scene was calm after firefighters cordoned off the area.

Smoke inside Hong Kong's World Trade Centre

Credit: Gigi pic.twitter.com/HeixnxmtRk

— SCMP Hong Kong (@SCMPHongKong) December 15, 2021

-with AAP