HONG KONG (AFP) - A firefighter died on Thursday (June 23) after battling a fire in Hong Kong that has lasted for almost three days, the second killed by the rare large blaze in the southern Chinese city.

The fire broke out at a self-storage unit in a multi-storey industrial building in the East Kowloon area on Tuesday morning.

Firefighters have been struggling to contain the blaze, which has already claimed the life of a senior station officer.

Fireman Hui Chi-kit, 37, died while fighting the fire on Thursday night, while two others have been sent to hospital with serious injuries.

"We had a team on the third floor extinguishing the fire... When there was duty handover, they discovered Hui was unconscious," fire department director Lai Man-hin told reporters.

"All of our colleagues immediately began rescuing him and brought him to the ambulance," said Lai, who looked exhausted.

Television footage showed firemen carrying an unconscious colleague from the burning building and paramedics conducting cardiopulmonary resuscitation on him.

Two firemen were hospitalised on Thursday in serious condition, a government spokesman told AFP, while nine others have been discharged.

The fire department said they had encountered difficulty in controlling the fire, which broke out in a building containing 200 storage units.

"One of the biggest difficulties is that the temperature is very high... every unit is separated by a metal sheet," Lam said.

Large fires are rare in Hong Kong. In 2011, a blaze engulfed a residential tower and tourist market, killing nine people and injuring 30.