He says there's "no point denying the emotion because that just makes the emotion increase".
To do this, you've got to "name it out loud", telling your child: "Yup, that was a really scary thing to have happen."
But it's important to then instil some resilience by way of positive details from the incident. In this case, Wallace suggests saying: "'The police responded really quickly and the bad man's in jail.'
"If you, as a parent are like, 'yup, this is really tragic but I know we're going to rise above this,' that gives them security."
He says turn the focus to talking about "the heroes", the servicemen and women and people who helped, "so kids are left with a sense of hope".
ZM host Vaughan, who has two young daughters, notes how instinctive children are when it comes to picking up on parents' emotions. Mikaere-Wallace agrees, adding it's important to make the distinction between off-loading your concerns onto your children and explaining the need-to-knows.
The amount of information you should discuss should be based on their developmental understanding too, rather than their age, specifically.
"It's not so much that there's a certain age, the parents will know that."
Mikaere-Wallace shared that his grandson, 4, was staying with him over the weekend and he chose to tell him the bare minimum about the incident.
"All he knew was there was a bad man with a gun. I'm not going to talk to him about Muslim faith, I'm just going to say, 'yup, there was a bad man with a gun but the police caught him really really quickly and he's in jail and now everybody's helping all the people that are sad'. And that's the only explanation I have to give to a 4-year-old."
Mikaere-Wallace says it's a time where families should make an effort to be together and suggests getting outside and playing with your kids.
"The way the brain works is something like this sort of speeds up the brain ... so that puts them into survival brain. So what you've got to do is slow down the kid's internal clock. And that's not through video games and media and everything coming at them full on. That's through playing Monopoly, and going outside and playing, interacting with people."