Royal Canadian Mounted Police (RCMP) are still investigating the cause of an accident at the Peace Arch crossing Tuesday evening.

A driver from B.C. crashed into several other cars and a guard rail at a high rate of speed before coming to rest just north of the Canadian side of the Peace Arch crossing. The 29-year-old woman, who has yet to be named, was traveling south on Highway 99 at about 8:30 p.m. on Tuesday, June 26, when she struck several other cars and a guardrail, according to reports from the Blaine Police Department. The woman’s car came to a stop south of the Peace Arch monument, just north of the U.S. customs inspection booths.

A Blaine police officer, who was near the border investigating an unrelated incident, was the first to arrive at the scene of the accident. The officer found the woman slumped over the center console of her car, not breathing.

The Blaine officer and U.S. Customs and Border Protection agents were able to stabilize the woman and keep her airway open until medical help arrived. Medic crews from B.C. air-lifted the woman from the scene to a hospital in Canada. RCMP officers impounded the woman’s car as part of their investigation into other accidents in which the woman is thought to have been involved in Surrey.

Sgt. Peter Thiessen, RCMP senior media relations officer, said the cause of the accident is still under investigation and could not say whether the woman’s loss of consciousness was due to health issues or drugs. The 29-year-old woman has not been charged with any crime.

Thiessen said he did not believe any other vehicles were involved in the accident. Investigators have not yet determined how fast the woman was driving when she crashed.

Jane Powell, a witness to the aftermath of the accident, told The Northern Light in an email that the small, dark blue sedan had driven over a curb just north of the U.S. customs inspections building and destroyed a handful of permanent traffic signs. Powell said the sedan had been damaged along the entire length of the driver’s side, with the rear view mirror hanging from the driver’s side door and the left side of the windshield shattered.