A two-vehicle collision happened shortly after 2pm at the Shilbottle crossroads, south of Alnwick.
The southbound carriageway was closed for around 90 minutes but has now reopened.
A Northumbria Police spokesperson said: “Shortly after 2.05pm, we were alerted to a report of two vehicle collision on the A1 southbound near the Longframlington junction.
“Passengers from both vehicles required medical assistance.
“Emergency crews remain at the scene.”