BOISE -- A 25-year-old man was seriously injured when he was struck by a vehicle in downtown Boise early Sunday morning.

Officers were called out to the area of 8th and Franklin streets at about 3 a.m. after a passerby found the young cyclist lying unconscious in the street.

Eric Siegrist was rushed to Saint Alphonsus Regional Medical Center in Boise by paramedics.

Boise Police spokeswoman Haley Williams said officers were originally not certain what had caused the cyclist's injuries. As they investigated, a driver returned to the scene and told the officers he had hit a man on a bicycle about 20 minutes ago.

The driver, whose name has not yet been released, told investigators he was driving on 8th Street when Siegrist pedaled out of an alley between Washington and Franklin streets without stopping, and was struck by the driver's vehicle.

Siegrist was not wearing a helmet, police say. He was listed in critical condition at the hospital Monday.

Williams said investigators are continuing to speak with the driver, and charges are pending in the case. He will face a felony charge of leaving the scene of an accident resulting in injury.