Prince George RCMP say the incident happened before 4 a.m. PT at Kwitzil Lake, which is also known as Gravel Pit Lake, about 40 kilometres west of Prince George along Highway 16.
Cpl. Craig Douglass said the area was the site of a large party overnight, and that witnesses reported seeing a vehicle going into the lake, with possibly two people inside at the time.
Search and rescue crews located a vehicle in the water Sunday morning. An RCMP recovery dive team is expected to arrive in the area Sunday afternoon, he said.
"This investigation is in its early stages," Douglass said in a written statement. "At this time, no determination has been made as to what led to the vehicle going into the water."