More than 58 people were injured when Typhoon Hagupit hit Hong Kong Wednesday, grounding flights and closing schools.

Trees were felled and roads were flooded as torrential rains and gale-force winds lashed the former British colony, shutting the airport for 12 hours starting at 9 pm (1300 GMT) Tuesday.

By 6 am Wednesday, a government spokesman said 58 people, aged 6 to 89, had been treated at accident and emergency hospital units across the territory from injuries received in the storm.

Thirteen people were still being treated Wednesday morning. Three were in serious condition, and 10 were stable. The remaining casualties were treated and discharged.

Fifty-six flights were cancelled, 92 flights were delayed and three flights were diverted. There were 16 cases of flooding, and seven cases of scaffolding collapsing across the city of 6.9 million.

The typhoon, one of the strongest to hit the region this year, passed within 180 kilometres of Hong Kong and was expected to make landfall Wednesday morning in neighbouring southern China.

Schools and courts remained closed Wednesday as cleanup got under way, but public transport was operating as normal, and Cathay Pacific and Dragonair resumed flights from 8 am.

A spokesman for the Hong Kong Observatory weather centre told the government-run radio station RTHK that the storm would have been "devastating" had it scored a direct hit on the city.

"It is one of the strongest typhoons we have seen for quite a while with winds of 170 kilometres per hour," the spokesman said.

Forecasters said Hong Kong would continue to be battered by storm-force winds and heavy rain throughout Wednesday.

Typhoon Hagupit, whose name means "lashing" in Filipino, caused five deaths Monday when it raged across the northern Philippines before crossing the South China Sea to Hong Kong.

Hong Kong was hit directly three weeks ago by a weaker typhoon, which sparked a high alert from authorities but caused relatively little damage.

The city, which used to suffer devastating land slips during typhoon season, has developed elaborate typhoon defences and warning systems in recent years.