A hawker stall that sold children's clothing has been identified as the source of the city's deadliest fire in 15 years, but a four-month investigation has found nothing to suggest arson.
Nine people were killed and 34 injured in November's blaze, which police say started inside the booth near the exit of a staircase shared by two eight-storey buildings at 192 and 194 Fa Yuen Street, Mong Kok.
The nine victims were found collapsed on the staircase after more than 300 firemen took eight hours to douse the flames. The fire raised concerns over the dangers of subdivided flats, in which many of the dead lived, and the safety of hawker stalls.
'The stall is the centre of our investigations into the blaze,' one police officer said. 'We are focusing on whether an electrical appliance inside the booth burst into flames because of a short circuit and then ignited the stall.'
The electrical appliances fixed in the booth included an electric fan, a spotlight and several lamps. The stall was surrounded by thick nylon sheets with a metal net.
While arson has not been ruled out, investigators say there is little evidence to suggest the fire was started deliberately. The officer said no accelerant was found at the booth and CCTV footage did not show anyone acting suspiciously in the area.
'The stall owner had no dispute with anyone else and had no debt problems,' he said. 'We found no reason why it would be targeted.'
Police believe wind spread the fire to stalls on the other side of the road before it spread to six blocks of flats.
Officers checked hundreds of hours of CCTV tapes, interviewed at least 400 people and collected between 300 and 400 pieces of evidence from the scene.
'After the blaze, we deployed more than 300 officers to investigate in the first week and interviewed 300 to 400 people, including hawkers, residents and witnesses in two to three days,' the officer said.
Police have also received preliminary reports from the Electrical and Mechanical Services Department indicating that the possibility of an overloaded electric switchboard having caused the blaze is low.
Detectives are still looking into all possible clues including the possibility of arson.
Although there is no evidence of arson, a senior police officer said: 'We are keeping an open mind.'
He said some possibilities could not be ruled out because 'most exhibits taken from the scene were badly burnt or turned into ashes'.
Arson was suspected because firemen found two rows of stalls ablaze when they arrived.
It is unclear when a full report will be ready as police are still waiting for final test reports from some government departments.
Police will also seek the views of an independent expert - Professor Ho Siu-lau, the head of Polytechnic University's electrical engineering department - before submitting a full report to the coroner.
The blaze broke out in the early hours of November 30.
Following the blaze, the Buildings Department targeted 339 similar buildings looking for fire hazards and illegal building work. The checks are due to be completed by the middle of the year. Government checks on hawker stalls were also stepped up.