Electric taxis have been left without power after a quick charger overheated in Kowloon, leading the operator to shut all three of its charging stations.
The taxi maker, BYD Auto, is investigating the cause, along with CLP Power and The Link Reit, which operates the car park at Oi Man Estate in Ho Man Tin, where the charger is located.
A report will be filed with the Electrical and Mechanical Services Department.
BYD's stock fell about 9.27 per cent amid a 2.88 per cent decline in the Hang Seng Index.
At 3pm on Tuesday, a driver connected his taxi to the charger, one of six at the car park, and went for lunch. Smoke was later seen coming from the unit. A motorcyclist helped to douse the charger with an extinguisher.
BYD, which counts Warren Buffett among its investors, denied that there had been a fire and said the unit had only overheated.
"There was an overheating of the interface that links to the power grid, which led to the meltdown of some plastic covers," a spokeswoman said. "The smoke then lightly darkened the area around [the unit]."
She said the charger was being examined. All 12 other chargers at three different locations across the city have been shut down.
The only functioning charger is operated by BYD's local partner, Sime Darby.
A spokesman for CLP Power said it had installed the charger and connected it to the power supply and would help in the investigation.
The connection had passed the required safety tests, he said.
Wong Chung-keung, chairman of the Hong Kong Taxi and PLB Association, which worked with BYD to bring 10 of the taxis to the city about a month ago, said nearly all the vehicles would be idle.
"Some drivers have switched to LPG taxis for the time being. I hope they will not be deterred by this single incident," he said.
Wong said some drivers had told him that the charger had not been working properly and some had avoided using it.
Eric Cheng Ka-wai, a professor of electrical engineering at Polytechnic University, said the incident was likely due to poor contact between the power supply and the charger.
"The contact point has to be fixed by screws and if it is loose, it will lead to a rise in resistance and result in overheating," he said.