A 17-year-old runner was critically injured Saturday night while taking part in a fundraising event for the Bakersfield Police Department's K-9 unit.

The teen was hit by a Honda Accord on Calloway Drive, near the intersection with Stockdale Highway, around 9:15 p.m. His name was not released. Police said Sunday he suffered major injuries and was in critical condition at Kern Medical Center.

The driver of the car, 19-year-old Casey Geiger, may have been under the influence of marijuana, police say. Geiger took a blood test and was released pending results.

The nighttime run followed the Kern River bike path after leaving the Park at River Walk at 8:30 p.m. It was the 8th annual Howlin' at the Moon Fun Run.

Police, in their press release, say they don't know why the runner "diverted from the planned route" and ended up on Calloway in the path of an oncoming car.

But Californian sports writer Zach Ewing, who took part in the 10k race and watched the teen head up the wrong fork, said the path was pitch black and confusing at that spot.

"I was totally unsure for about half a second," Ewing said of the unmarked split.

By that time twilight had faded to dark and the only course markings Ewing had seen were glow sticks that occasionally popped up along the way.

The 17-year-old was two spots in front of Ewing when the unmarked fork loomed.

A man between them shouted: "Hey bro, you need to go right," Ewing said.

But the teen apparently didn't hear the advice.

Ewing veered right because the runner in front of him seemed sure of the route. The teen disappeared up the left fork. Just around the turn, Ewing saw a light and knew he was on the correct path.

Less than a minute later, Ewing heard honking, squealing tires, car doors slamming and a female voice saying "Oh my God."

After reaching the finish line, Ewing heard that a runner had been hit on the course.

Online court records show Geiger, the driver, pled no contest to charges from a November 2008 misdemeanor battery arrest; a sentencing hearing is set for December. An October arrest on suspicion of misdemeanor possession and use of a controlled substance was scheduled for a hearing last week and results were not immediately available Sunday.

Police are asking anyone with information to call the traffic investigations unit at 326-3967.