This is reported by Stuff with reference to local police commissioner Mike Bush.
According to him, among the detainees are three men and one woman.
Also, the police found a car with an explosive device. The bomb was cleared.
The publication claims that as a result of the shooting killed at least 30 people.
Earlier it became known that one of the attackers is an Australian. Before the attack, he wrote a manifesto in which he stated his intentions.