A 17-year-old was indecently assaulted while walking the family dog in Whanganui on Sunday.
The teenager was walking across the left side of the city's Dublin St bridge at about 3.30pm with the dark-coloured labrador.
She overtook a man walking by himself in the same direction and carried on walking in front of him.
When she got to the Somme Parade side of the bridge, she turned left and left again, onto the walkway under the bridge.
She was then approached from behind and indecently assaulted by the man she had overtaken on the bridge.
The victim turned and swore at the man, who ran off along Somme Parade.
He was seen by a witness crossing the road and running up Plymouth St.
The man is described as early-mid 20s, approximately 1.9 metres tall, of average/medium build, with brown eyes and short brown hair.
He has acne scarring or freckles on his cheeks and was wearing a black t-shirt with white on it, jogger-style shorts and sneakers.
Anyone with information should contact local police.