A woman is in a critical condition after crashing into a tree in the Waikato.

Police said they were at the scene of the crash on Tauhei Rd.

The driver, a woman in her 30s, was in a critical condition and had been transported to Waikato Hospital by Westpac Helicopter.

Diversions were in place along Cameron Rd and Tauhei Rd and the intersection of Matuku Rd and Tauhei Rd.

The Serious Crash Unit were in attendance.