Joel Cauchi, a 40-year-old attacker who stabbed those around him with a large knife, was shot dead by police after killing six people, five women and one man. Several people, including a baby, were injured in the incident.
Authorities said the attack was most likely "linked to Cauchi's mental health".
However, Webb said the attack was not an "act of terrorism" and police did not believe there was an "ideological motivation".
Cauchi, from the neighboring state of Queensland, is still on police record, while it was emphasized that the small warehouse the attacker kept in Sydney did not give any clues about the motive of the attack.
Ashlee Good, the 38-year-old mother of the 9-month-old baby girl who was injured in the incident, also died. Eyewitnesses said that Good tried to give her baby to those around her immediately after the attack.