"It's just tragic," he told the Herald.
"You can handle it when someone's got cancer, you know at some point they're going to go, but this was such a shock."
Her workmates, many of whom Grice had personal friendships with, were upset but coping, he said.
"It's pretty hard but they're coping okay."
Willoughby described Grice as an extremely caring person, with a "beautiful family".
"She's very close with her husband."
Grice's husband declined to comment this morning, saying the family would prefer to grieve in private.
Cafe Greenfingers head chef Mehdi Soheili was busy in his cafe, at the intersection of Shore Rd and Orakei Rd, about 9am yesterday when a member of the public ran in saying a group of people had been hit by a car outside Palmers Garden Centre.
"I just ran out and tried to do first aid as best as I could, tried to give people water and tried to calm the situation down, as you do, as any Kiwi would."
Soheili said just before running out of the kitchen, he told his sous chef to take over, grabbed his first aid kit and arrived to see a lot of people standing around in shock.
He tried to calm the situation and called 111.
The woman who was fatally injured had been thrown into a nearby bush, he said, while two other people - a man and a woman - were laying injured on the ground.
"I just did my best to get people to also look after the lady who was in the car ... my heart and head are still pounding at the moment .. but it's probably still better to work. We had the opportunity to [not] work but our boss is very understanding and very supportive. Instant reaction."
Police confirmed yesterday a female pedestrian died at the scene.
St John ambulance treated one person with moderate injuries and one person with minor injuries.
The Serious Crash Unit is investigating the incident.