Two people were killed early Sunday morning when a speeding Jeep lost control on a San Diego County freeway interchange and plunged off a bridge into the Sweetwater River in Chula Vista, the California Highway Patrol reported.

The crash occurred shortly before 1 a.m. Sunday on State Route 54 at the transition to southbound Interstate 5, when a witness reported seeing the Jeep traveling at high speed with sparks flying before the vehicle launched off the elevated section and fell into the river below.

A good Samaritan and a Chula Vista police officer separately attempted to rescue the driver and passenger from the submerged vehicle, but both occupants were pronounced dead at the scene. The CHP is investigating the crash with impairment and speed as suspected factors.

The freeway interchange was shut down following the crash and reopened by approximately 7:30 a.m. Sunday. The San Diego County Medical Examiner's Office was called to the scene to identify the victims; their names had not been released as of Sunday afternoon.

The CHP is leading the investigation. Anyone with information about the crash can contact the CHP San Diego Area office.