HONG KONG, DECEMBER 15

Hundreds of people were trapped on the rooftop of a Hong Kong skyscraper after a major fire broke out on Wednesday, as firefighters rushed to rescue them and put out the blaze.

The fire started in the early afternoon at the World Trade Centre on Gloucester Road in the city's popular Causeway Bay shopping district, according to a government notice. The 38-story tower houses both offices and a mall.

At least 12 people were sent to hospital for treatment, according to authorities.

Dense smoke was seen billowing out from the building, and photos and videos from those trapped inside showed poor visibility as smoke filled restaurants and stairways of the building.

About 300 people evacuated to the top of the building while waiting to be rescued, police told local media.

Tens of people trapped in the building had also jammed into narrow areas on an open-air podium on the fifth floor, peering over the edge as they awaited rescue.

Preliminary investigations by the police suggested that the fire had broken out in the electrical switch room located on the first floor of the shopping mall, before spreading to the scaffolding that surrounded part of the building, according to local newspaper South China Morning Post.

Firefighters had used an extendable ladder to rescue the people on the fifth floor. Other people were said to be trapped in restaurants in the mall, added the local newspaper.

A total of about 1,200 people were evacuated from the building, according to local media reports.

The fire was upgraded to a level three incident, according to a police notice. Fires are graded on a scale of one to five, with five being the most severe. As of 3:06 p.m., authorities said the fire was under control.

Two breathing apparatus teams and two water jets were mobilized to help fight the blaze, police said.