The injuries included burns to legs, arms and faces
Thirty people were treated for injuries in Hong Kong after they were splashed by a corrosive liquid.
Two bottles of what is thought to be acid were either thrown or fell from a building into crowds of shoppers in the Mong Kok district.
Those who received medical help - 14 women and 16 men - suffered burns to the legs, arms and faces.
Police are linking it to an incident in December when 46 people were hit by acid on the same street.
No-one has been arrested in connection with either incident.
Police say whoever is responsible faces a possible charge of intent to cause grievous bodily harm, which can lead to life in prison.
After the December incident, police offered a reward of $12,900 (£8,000) for information leading to an arrest.
"We will find out whether the two cases were done by the same person as soon as possible," said Superintendant Leung Ka-ming.
Firefighters helped those affected clean the liquid from their arms and legs before sending them to hospital.
Samples of the fluid are being tested in a laboratory to determine exactly what it is.