Police say a woman was sexually and physically assaulted in broad daylight in Lower Hutt.
They said the woman, in her 30s, was having her lunch break in Melling when a man attacked her at about 1pm yesterday afternoon.
Detective Sergeant Nick Pritchard said the attack was violent and cowardly.
"The victim was taken by surprise; she did not see the person appear until he was very close to her."
He said the woman was grabbed from behind while walking along the Hutt River bank, threatened with a knife and then kicked in the head and stomped on.
Mr Pritchard said the man was of slim-to-average build, with light brown skin, and aged in his 20s.
He said the attacker was wearing a dark-coloured long sleeve top, knee-length shorts, a hat and also gloves, which are possibly fingerless.
The police have asked anyone with information to contact them.