A family is searching for answers after a 15-year-old boy and his girlfriend were killed in a police pursuit that ended in a head-on collision in Hamilton, Ont. on Thursday morning.

The fatal crash took place as Waterloo Regional Police were chasing a vehicle after being called about a possible abduction or assault of a female in Cambridge, Ont.

Waterloo Regional Police say they received a call around 9:30 a.m. on Thursday. After locating a car driven by a male and carrying a female passenger, police began to pursue the vehicle when the driver refused to stop.

After a 20-minute chase, the vehicle slammed into an oncoming transport truck near Hamilton.

The teenage couple was pronounced dead at the scene. No other injuries were reported.

Victims of the crash have not been identified by the police but CTV Toronto confirmed the driver to be Nathan Wehrle after speaking with his older sister Chloe Wehrle on Friday.

Chloe said she has questions about what happened to her brother.

“I just need some answers. Something to help,” she said.

She says the actions of her brother were out of character, commenting that “stealing cars was his thing” but not “killing and abducting people.”

Wehrle said the vehicle, a red Pontiac G6, belonged to her friend and had been stolen by her brother.

She says her brother would “never trap somebody.”

“I just want everyone to know my brother would never do something like that,” she said. “Ever since he was a kid he would just spend all of his birthday money on his friends. There was nothing else that he would rather do than to just make somebody else happy.”

Ontario’s Special Investigations Unit is now investigating the crash and an internal investigation has been turned over to members of the OPP.

“Because this primary investigation… does involve members of our organization, we’ve asked the Ontario Provincial Police to conduct an independent investigation,” Insp. Michael Haffner told CTV News on Friday.

“We’re asking the OPP to conduct a fair and transparent investigation on our behalf.”

A pizza place where the abduction investigation started has also provided surveillance footage to officers to help with the review, police said. The footage has not been publicly released.

With files from CTV Toronto’s Kayla Goodfield and CTV Kitchener’s Ryan Flanagan