Updated 1.24pm: The police officers who rescued a woman from the Waikato River early this morning are being praised.

Emergency services were called to the river, near the Fairfield Bridge at around 1am after nearby residents reported hearing screaming.

A 17 year old woman was in distress 10 metres offshore.

Sergeant Murray Stapp says an officer swam to rescue the woman as she was going under and he got her head above water and three helped get her to shore.

He says he has nothing but praise for those involved in the rescue.

The woman is in a serious condition in Waikato Hospital and police are investigating why she was in the river.