LIVERMORE -- An 18-year-old Livermore man was seriously injured late Monday when he was hit by a station wagon while walking on Highway 84, police said.

The collision happened at about 10:21 p.m. at the intersection of Isabel Avenue on Highway 84 and Airway Boulevard, Livermore police Sgt. John Hurd said. Officers arriving found the victim after he was hit by a Honda station wagon driven by a 44-year-old Pleasanton man, Hurd said.

The extent of the 18-year-old's injuries was not known immediately, but Hurd said he was taken to a hospital in an ambulance.

Officers interviewed the driver of the station wagon, who cooperated with police, Hurd said. Police say drugs and alcohol were not a factor in the collision.

Highway 84 was closed in the northbound direction for several hours, as traffic officers investigated. It was reopened before the morning commute.

Police did not identify the driver or the victim.

Anyone who witnessed the collision is urged to contact Livermore police at 925-371-4850.

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.