Two children were killed last Friday after their vehicle lost it’s brakes and struck a tree, ultimately splitting the car in half.

A California Highway Patrol sergeant said the children were brothers, one about 5 years old, the other a toddler. Their mother was driving the car during the crash and was airlifted to UC Davis Medical Center.

Although investigators have not reached a final conclusion on what exactly caused the crash, all evidence so far is pointing towards brake failure. “There is not a lot of tire friction marks on the roadway that would indicate, when someone is about to crash, to slam on the brakes and slow the vehicle,” said one officer. “Usually, the tires put rubber down on the roadway, and we don’t have any of that at the scene.”

Other witnesses say the condition of the road is to blame.

“It’s a very uneven and rough road,” said Tim Neuharth. “I don’t care for it. I don’t know why this hasn’t been taken care of a long time ago. It should have been. It’s a much-used highway. It’s a state highway, 84.”

Farm workers heard the impact of the crash, ran to the scene and reported it, it is not clear if anyone saw the accident happen.

The driver was talking to officers when she was being taken to the hospital. She is expected to fully recover.