Firefighters are battling a blaze that broke out at the Chinachem Tower in Hong Kong’s central business district after scaffolding on the building caught fire on Saturday afternoon, with three people trapped in a lift.

Police said they received reports of a fire at No 34-37 Connaught Road Central, the address of the tower, at about 4.24pm.

“Informants said a scaffolding facing a back alley of a building caught fire. There is no report of injury. Three men were said to have been trapped in a lift,” a police spokesman said.

Three adults and a child were also reported to have been trapped in a nearby convenience store, according to the spokesman.

Pictures and videos circulated online show flames engulfing external scaffolding and black smoke billowing from the tower.

Some media reports said there were explosions.

The Fire Services Department said the blaze was classified as a No 3 alarm and about 30 people were evacuated. Hong Kong uses a five-stage alarm system to rate the severity of a fire, with No 5 the most serious level.