Ms Wallace said the situation was "not an everyday occurrence".
Two investigations have been launched into the shooting.
Detective Inspector Dave Lynch said a woman and two children had fled before police arrived to find the man in a garage about 5pm yesterday.
The man appeared to be drunk and "extremely aggressive" towards police.
Officers tried to negotiate with the man but he armed himself with a garden spade and an LPG cylinder that was leaking gas.
Police used pepper spray to little effect and shot him with a taser.
Mr Lynch said the man continued to display aggression towards police and refused to comply with their directions.
"He advanced upon police and was shot in his leg."
Mr Lynch said preliminary analysis of video footage confirmed the "courageous actions of the officers involved".
Ambulance staff were already on the scene and gave the man immediate first aid before taking him to Middlemore Hospital.
He was today in a stable condition with injuries that were not life-threatening.
Charges were yet to be laid.
Mr Lynch will lead a police investigation into the shooting, with oversight from Detective Superintendent Andy Lovelock of Upper North Districts police.
A separate investigation will be conducted by the Independent Police Conduct Authority.