'Took it like the champ': Toddler 'punched in the head' by random man in supermarket

A toddler was allegedly punched in the head by a random stranger in a New Zealand supermarket over the weekend, prompting a police investigation.

Shane Madden said his 18-month-old son "took it like the champ he is" when an unknown man hit him in the head at a Park'n'Save supermarket in Wairau in Auckland's south on Sunday.

In a post on Facebook, Shane said his son Theodore did not cry but was more surprised by the alleged assault.

"I think he was more a bit confused about what had happened and thought 'My head hurts and I'm not sure why', and seeing the boy getting carried off I think he was just a bit concerned," Shane wrote in the post.

The Madden family were at the Park'n'Save in Auckland when the random man allegedly attacked. Source: park'n'Save

Theodore's mother Shelly Madden told Newshub the man, who they believe to be intellectually disabled and aged in his 20s, was waiting with another man they believed to be his father or carer when he became "a bit irritated".

"The next thing I knew he had turned around, I think in frustration or maybe being a little bit overwhelmed in the situation he was in, and just lashed out," she said.

"It just happened that we were right next to him and with a closed fist, [he] just punched my son Theo in the side of the head."

Theodore Madden took the hit 'like the champ he is', his father said. Source: Supplied

The older man immediately grabbed the younger man and "removed him from the situation" without saying anything, the mother said.

The family were left stunned but Theodore soon began vomiting.

He spent Sunday afternoon and evening at Starship Hospital, but doctors were not certain whether the illness was caused from the shock of the punch or a viral infection, Shelly said.

The Facebook post. Source: Facebook/Shane Madden

Otherwise, Theodore was okay.

"He's a little bit clingy… and a usual toddler, but he's been pretty good today," Shelly said.

The family said they were concerned for the alleged attacker, who they "don't any malice" toward but hope it does not happen someone else.

Theodore vomited and was taken to hospital but was otherwise fine. Source: Supplied

"We just really want to... make sure that he's got support for him, because I'm sure his carer will be feeling awful about what happened," she said.

A police spokesperson told Newshub an investigation into an alleged assault on an 18-month-old at a supermarket had been launched.