Smith was in the passenger seat of Cory Sater's Jeep in Feb. 2011 when it allegedly hit Charlene Raeveley and Lorraine Cruz, killing the women instantly.
- Read more about the hit-and-run
Smith said he and Sater had been drinking at the Lougheed Village Bar & Grill and, just before midnight, they left to retrieve money from Sater's house so they could go drink some more.
The tragic events unfolded at Lougheed Highway and Pitt River Road, after the pair left Sater's house.
Smith testified that he saw two women, one blond and one dark-haired, get hit. He said he was shouting "Stop! Stop! Stop!" at Sater.
"I apologize to everybody," Smith said in court. "It's very hard for me with the families here. I believed they were killed. I was freaking out. I was in a state of shock because I witnessed the collision.
"When you're going that fast the probability of anyone surviving is slim."
Smith said that instead of stopping, Sater kept driving along Lougheed Highway toward a cul-de-sac in the Cape Horn area. There, Sater knocked on the door of his girlfriend's house, but there was no answer.
Smith testified that Sater was in denial: he didn't believe what just happened, and kept talking about his own children.
Leaving the Jeep, the pair then walked to Sater's brother's house, and told him there was a bad accident. Both Sater and Smith took taxi rides home.
Smith said that he was headed to talk to the police the next morning when he got a call from Sater's brother, telling him not to go because a lawyer would be going with Sater to the police.
Sater is on trial for 10 charges including dangerous driving causing death, impaired driving causing death, and failure to remain at the scene.
The Crown maintains Sater drank six rye-and-Cokes and two shots at the pub in the time leading up to the accident.
The trial continues Friday.