SAN DIEGO — A man riding a motorized scooter was seriously injured in a hit-and-run collision Thursday in the Cortez neighborhood, authorities said.

The incident occurred around 8:24 p.m. when an unknown vehicle was driving on the 500 block of Ash Street in the westbound left lane, the San Diego Police Department explained.

At that same time, authorities say a 22-year-old man was riding a motorized scooter southbound in the bike path on the west side of 5th Avenue.

The front of the vehicle struck the man on the scooter, then police say the driver fled the scene.

The scooter rider sustained an open skull fracture and brain bleed. Police say his injuries are considered life threatening.

San Diego Police Traffic Division is investigating. Anyone with information related to the hit-and-run is encouraged to call Crime Stoppers at 888-580-8477.