Another acid attack in Sham Shui Po last night might be linked to three previous attacks in the district, police said. At least one pedestrian was burned when a Blue Girl beer bottle full of what police termed 'a strong acid' was thrown from a building in Sham Shui Po into Apliu Street near No 212 Apliu Street at about 6.30pm. Police said the other attacks in the district also involved acid contained in Blue Girl beer bottles. In last night's attack, the bottle of acid landed on the zinc roof of a stall, splashing at least one pedestrian, who complained to the stall-holder about a burn to his cheek. The stall-holder helped the middle-aged victim wash his cheek with water and the man left the scene. A woman stall-keeper said: 'There was a bang, and people looked up and saw lots of smoke. And someone called the police ... the bang was loud. The pedestrians ran away immediately.' The latest attack is the 12th in a series of attacks in the city - eight in urban areas and three in the New Territories - since December 2008, which have injured more than 100 people. Mong Kok has been the worst hit with all attacks there involving plastic bottles containing drainage solvent easily available in stores. A reward of HK$900,000 for information on the Mong Kok cases remains unclaimed. 'The fluid has been examined initially by a scientific evidence officer. He said it is a strong acid,' Stephen Tarrant, assistant Sham Shui Po district commander (crime), said, adding that laboratory tests would fully reveal the chemical make-up of the bottle's contents. Officers were seen collecting fluid samples from the stall roof, while others filmed nearby pedestrians and surrounding buildings and footpaths. Tarrant said he did not know whether the attack was linked to others involving acid in the city. Police have offered a HK$300,000 reward for information about three previous acid attacks in Sham Shui Po in June and October. No-one was injured in those attacks. The first occurred on June 15 when a beer bottle containing acid was hurled from a building near 4 Fuk Wa Street. Similar attacks took place on October 24 and October 30 near 71-73 Fuk Wing Street and 185 Apliu Street. Tarrant said he believed this latest attack was random as he saw no evidence indicating the culprit had specifically targeted Apliu Street, even though this was the second case involving that street, which contains a popular market for electronic goods. Police want the male pedestrian hurt in the attack and any other witnesses to come forward to assist with their investigations. Sham Shui Po District Council may call a special meeting to discuss the latest acid attack, Chan Tung, the council chairman, said. He said since the previous attacks, the council had been discussing whether closed-circuit television cameras should be installed in the district, but councillors could not reach agreement at a meeting on March 2 because they were divided on whether cameras might intrude on residents' privacy and whether there would be blind spots in camera coverage. Chan said the building at 212 Apliu Street, which police had previously noted had no security camera, metal gate or watchman, was next to a building suggested by police as good for the installation of a CCTV camera. 'No consensus was reached among 26 councillors ... My concern was about the camera's blindspots,' he said. In January, a man, 23, was arrested and charged in connection with a Causeway Bay acid attack in December which injured six people. This was the first arrest made in relation to the spate of acid attacks.