The principal of a high school girl who left another student with a mangled leg after a streaking stunt went wrong is interviewing the group of students involved.

Hamilton Boys' High School student Kyle Kirsten suffered a deep gash to his leg when hit by a girl from Waikato Diocesan School on the boys' field at lunchtime on Wednesday.

The girl was one of six involved in the end-of-year prank. Footage from social media app Snapchat shows they were wearing nothing but underpants and helmets.

One of the bikes rode over the Year 12 boy's leg, causing the rider to fall off. One of the girls is alleged to have given the middle finger before driving off.

Diocesan School principal Mary Curran said the school couldn't comment on potential ramifications for the girls as interviews were ongoing.

"This is the first step in an official process," she said.

"The principal will then give her report to the boards and they will decide on the action that will be taken."

The victim lay on the field until he was eventually helped off and taken to hospital. He is now recovering at home.

Kyle Kirsten's mother Ricky and his father Glen met police on Thursday.

The pair have described the girls' actions as a prank that "has gone a bit wrong".

"We are not going to press charges as we believe that the girls wouldn't have done this in the hope of hurting anyone," Ricky said.

"[Kyle] has a really bad cut on his shin but this has been stitched up and will recover."

Ricky said her son was a talented football player, but was she was certain the injury wouldn't jeopardise his future on the pitch.

"He will bounce back - I'm sure the injury will heal," she said.

The victim's family wanted it all to blow over, but boys' high principal Susan Hassall told the Herald she hoped charges are pressed.

"I think we need to send a strong message to young students that such reckless behaviour won't be tolerated."

The girls weren't invited on to school grounds and she called the speed at which they were driving the bikes "very dangerous".

"I'd call it more than a prank to be honest."

Waikato road police Senior Sergeant Pete van de Wetering told Fairfax police would be considering charges.

"While we understand it was a prank and a bit of spirited excitement by the girls, if there has been an injury, like there was in this case, there must be accountability."

Police would be speaking with the girls - who were all 17 years old - today.

- NZ Herald