Two of the Great North Air Ambulance Service (GNAAS) aircraft attended a serious four-vehicle crash on the A69 near Haltwhistle on Saturday.
The GNAAS crew performed advanced critical care including emergency open chest surgery and a roadside blood and plasma transfusions on one woman before accompanying her to hospital by road where she arrived in a critical condition.
A man with serious multiple injuries was also airlifted from the same incident.
Another woman was pronounced dead at the scene.
A GNAAS spokeswoman said: “Our thoughts are with everybody involved and the family and friends of those affected by the incident.”