Hong Kong media on Saturday reported that dozens of people were injured when two bottles of acid were thrown into a crowd in a popular shopping district.
Police spokeswoman Anne Lam said that at least 20 people were injured, but would not say what liquid was thrown.
Hong Kong Cable TV said some victims were splashed with acid in the Mong Kok district on Saturday afternoon. Television footage showed firefighters washing the liquid off victims' arms and legs before sending them to a hospital for treatment.
It was the second such attack in five months in the neighborhood.