An 18-year-old woman is in a critical condition after a crash east of Yass on Tuesday afternoon.

Delays are expected on the Hume Highway following the incident 15km east of the town.

At 1.45pm a RAV4 was travelling south on the highway when it crashed into a guard rail.

The teenager, a front seat passenger, sustained serious injuries and was airlifted to Canberra Hospital in a critical but stable condition.

Paramedics treated the 53-year-old male driver, as well as two back seat passengers, a 39-year-old woman and a 14-year-old girl, for lacerations.

The Crash Investigation Unit is at the crash site to conduct inquiries. One lane will remain open while it examines the scene.