The nine-year-old son of a Hong Kong couple was rescued in Macau yesterday after being kidnapped on his way to school on Monday. A woman was arrested when she allegedly took the boy to collect a $100,000 ransom. The woman, 34, an illegal immigrant who arrived in Macau five years ago on a two-way permit, was last night assisting Judiciary Police with their investigations. The boy, whose father is a businessman in Macau, was abducted by a woman while he was waiting for a school bus at 7.30am on Monday. Police spokesman Ko Kwok-keung said the woman assaulted the boy and threatened him in order to obtain his family's contact number. She then phoned his parents and demanded a $200,000 ransom but it was later agreed to halve the sum. Police said the boy's parents were told to place the ransom money in a dustbin on the ninth floor of a building by 2.30pm, but no one had collected the ransom by 9pm. They were again contacted and instructed to place the ransom in another dustbin in a nearby street at 1pm yesterday. Police said they laid an ambush and arrested the woman as she arrived with the boy. Officers believed the arrested woman lived near the boy's home.