Five young men between the ages of 16 and 24 were arrested on Wednesday in early morning raids in Sydney as a part of an investigation into last week’s murder of an accountant in a Sydney suburb, which New South Wales Police deputy commissioner Catherine Burn called a “terrorism event.” Over 200 police officers raided four different houses in Australia’s largest antiterrorist raid this year, Reuters reports. Curtis Cheng, a 58-year-old accountant who worked for the police in a civilian capacity, was shot and killed in the western suburb of Parramatta around 4:30 p.m.