A drag race between two speeding cars on a residential street in Barrhaven is to blame for the death of the teenage driver of one of the vehicles, an Ottawa court was told Monday.

"The cars were going fast and were continually accelerating," said witness Jennifer McFarlene. "One trying to keep the lead, one trying to get in the lead."

Nineteen-year-old Kareem Alli pleaded not guilty to charges of criminal negligence causing death by street racing and dangerous operation of a motor vehicle causing death while street racing.

Prosecutors allege that Alli and Christian Williams, 18, were both racing their cars down Claridge Drive when Williams lost control of his car and crashed into a light post on June 22, 2010.

"Williams went flying by," said Chris Richardson who was riding in one of the vehicles and a friend of both men. "As he came to overtake, he started drifting and hit the post."

Williams died at the scene.

The trial is ongoing.

With a report from CTV Ottawa's Vanessa Lee