"At first I was angry, and then when I actually saw them I thought 'Oh my god, they're babies.' What the hell are you doing out at this time in the morning?"
Amanda was concerned parents did not realise their children were out wandering the streets in the middle of the night, and possibly sneaking out and leaving their own houses unsecured.
"They're walking around Whanganui all hours of the night - parents don't know they're out there doing it," she said.
"They're going to walk onto the wrong property one day and someone's going to sic their dog on them and they're going to get chewed up."
Constable G Singh said Whanganui Police had not had many problems with Pokémon Go users.
"We honestly haven't had too much of that," he said. "We've had just general calls in about people congregating in certain areas, the odd traffic incident where people are pulling over pretty quickly to go catch a Pokémon."
Mr Singh wanted to remind people to be aware of their surroundings while playing the game, and to remember they still had to obey the law.
"Obviously Pokémon Go isn't a get out of jail free card. The laws still apply, you will still be dealt with for trespassing."
Mr Singh also wanted to remind parents to be aware of where their children were.
"If you can get in on the whole thing then be responsible by joining them," he said.