Police are appealing for witnesses following a collision on the A591 near Bassenthwaite.
Emergency services were called to the scene at 11.12am today (11th June).
The collision involved a car, driven by a man, from Leicester, and a motorcycle, ridden by a woman, 25, from Allerdale.
A Cumbria Police spokesman said: “The woman was flown by air ambulance to the Royal Victoria Infirmary in Newcastle, where she remains in a critical condition. The family are aware.
“The other driver was uninjured.
“The A591 was closed between the Castle Inn and the Bassenthwaite junction for around 5 hours whilst a forensic collision investigation took place.”
A Cumbria Fire and Rescue Service spokesman said: “At 10:05am fire engines from Keswick and Cockermouth attended a road traffic collision involving a car and motorcycle that was on fire on A591 Bassenthwaite Keswick.
“Firefighters assisted ambulance with casualty care, using one hose reel jet and a first aid kit.
“Fire fighters were at the incident for one hour and thirty minutes.”
Anyone with information should contact PC 2458 Defty or SGT Bainbridge 1929 on 101, referring to log 71 of June 11.