A six-year-old boy who survived a horrific crash that killed his parents west of Cornwall is undergoing brain surgery at the Children's Hospital of Eastern Ontario.

Bon Howland was listed in critical condition after a head-on collision on County Road 34 in South Glengarry Township Tuesday evening. He suffered a brain injury and broken bones in the crash.

"He's got a broken hip, broken arm, broken eye, cheekbone, brain hemorrhaging and some blood clotting," his sister, Ayesha Howland, told CTV Ottawa.

Bon's parents, Pamela Rathwell, 34, and Rodney Howland, 48, were killed when their car crossed into the path of a northbound vehicle at about 6 p.m. The family is from Alexandria, Ont.

The young child was in the backseat of the vehicle. The family's dog was also in the car and is being treated for a broken leg.

Ayesha, Howland's daughter from a previous marriage, told CTV Ottawa the family is in shock and is devastated by the crash.

She says they are now rallying around her younger brother, hoping for his recovery.

"It's just overwhelming to know that they both didn't make it. And my little brother, I just really feel for him and that's what's keeping me strong."

When Bon gets released from hospital, Ayesha plans to take care of him.

"I have a son whose four - another that's a year and a half. They're all going to be going to school together," she said.

Ontario Provincial Police say they don't know what caused the vehicle, driven by Rathwell, to cross the centre line. However, the family is convinced the crash was caused by heavy rain and poor weather conditions in the area.

"Their car hydroplaned. The tires slid in the water and hit another vehicle," Ayesha told CTV Ottawa.

The 70-year-old driver of the other car and his passenger were treated for minor injuries at Glengarry Memorial Hospital. They have since been released.

With a report from CTV Ottawa's Stefan Keyes