Police have arrested a 43-year-old Hong Kong man suspected of attacking four people, including two children, with a pair of scissors in a subdivided flat after asking to use their toilet. The arrest on Wednesday came a day after a search was launched for the suspect. Officers said he tailed a mainland Chinese man, surnamed Wu, to a home on Shek Kip Mei Street in Sham Shui Po at around 10.30pm on Monday night. Wu was returning to his sister’s subdivided flat. Sources said the suspect followed Wu into a lift and asked if he could use his toilet when they got out. “After entering the flat, the suspect used the toilet, then went to the kitchen and took a pair of scissors to attack the occupants for unknown reasons. He then fled,” a police spokesman said. Wu’s son, 18, a two-year-old boy and a three-year-old girl were all injured in the attack. The son suffered chest injuries and was in a critical condition in Princess Margaret Hospital in Lai Chi Kok while his father was in serious condition. The children were both stable. A police source on Tuesday said officers received multiple reports of a man wandering the streets nearby with a pair of scissors and muttering to himself. “We suspect he might be mentally disturbed,” the source had said. Wu’s sister was not home at the time of the attack.