Meeting the Australian prime minister for the first time, Ms Ardern joked there were no greater international issues facing world leaders.
Hassan Khalif Shire Ali fatally stabbed one man and injured two others after fire-bombing his car in the central city on Friday.
Hassan Khalif Shire Ali stabbed three men, killing one. Media reports have named the deceased man as Sisto Malaspina, the owner of Melbourne's iconic Pellegrini's Espresso Bar.
Transgender activist Lexie Matheson joined Breakfast this morning to discuss its significance and whether we should follow suit.