Two protesters were mowed down by a car early Saturday morning in Seattle, and the driver is now under arrest.

It happened at around 1:30 AM on a stretch of the I-5 that was closed to traffic. A car suddenly barreled down the road, striking 2 people. A 24-year-old woman is in critical condition with what troopers said were life-threatening injuries. Another woman suffered injuries that were described as serious.

Eyewitnesses told authorities they believed the incident was a “purposeful attack.”

The Washington State Patrol took the driver into custody. A spokesperson says it does not appear that impairment was a factor.