BOISE, Idaho — Authorities dug deeper Friday into what might have caused a dramatic SUV crash that killed an Idaho woman and her three children, while the kids’ schools arranged to make counselors available for grieving classmates.

Investigators so far have released few details about the crash, other than to say a witness reported seeing the vehicle accelerate from the side of the road before it went off a cliff and plummeted about 70 feet into a reservoir.

Deputies found no skid or brake marks near the cliff, the Ada County Sheriff’s Office said.

Also Friday, the county coroner’s office identified the victims as 40-year-old Noel J. Voermans, 13-year-old Anika Noel Voermans, 11-year-old Logan R. Voermans and 8-year-old Gwyneth G. Voermans, all of Boise.

The children all died of drowning associated with blunt-force trauma from the crash, the coroner’s office said.

The mother’s cause of death was drowning. Toxicology results won’t be available for several weeks, a spokesman said, and then they’ll be turned over to the sheriff’s office.

The SUV drove off a cliff Thursday morning near a bridge on State Highway 21. It then plunged into Lucky Peak Reservoir.

The top of the vehicle collapsed from the impact, deputies said. The SUV then sank about 40 feet before hitting the bottom.

Divers pulled the children’s bodies from the water about an hour and a half after the crash.

Noel Voermans’ body was trapped in the wreckage and removed once the vehicle was brought to the surface Thursday afternoon.