A police spokeswoman said they were called to the scene, near Forsyth Barr Stadium, at 9.15pm on Friday.
"A silver Holden Commodore crossed the centre line, travelling north on Ravensbourne Rd. It collided with a Kia Sorento, travelling south.
"The head-on impact caused significant damage to both vehicles."
One passenger received a split spleen and was in a critical condition, and four teenagers were in a serious condition with a mix of broken clavicles and head injuries.
They were taken to Dunedin Hospital. Two others also received minor injuries but were treated at the scene.
"A driver of one of the vehicles did leave the scene on foot.
"Inquiries were undertaken to try to locate them — we did area searches — but we were unable to locate them."
She said police were continuing to search for the driver.
A Fire and Emergency New Zealand spokesman said one person was initially trapped in a vehicle and was extricated by firefighters.
The road was completely blocked and traffic management was put in place for a time.
