An Irish woman was allegedly stabbed in the leg while she was out running on a beach in Nelson last night.
The incident happened near Tahunanui Beach about 9pm.
Police said two men were reported to have become involved in an altercation.
The 28-year-old Irish woman jogging in the area - who was not known to either of the men - was allegedly pproached by one of the men and stabbed in the leg with a large knife.
A police spokeswoman said it was unclear how the woman became involved but that she was running past at the time.
The woman received hospital treatment and was been left traumatised by the incident.
It's not known if she is a tourist or lives in New Zealand.
Police said they had arrested a 25-year-old Nelson man in relation to the incident.
He was due to appear in Nelson District Court this morning facing serious assault charges.
Police thanked members of the public who came to the woman's aid and helped police identify the alleged offender, who was arrested a short time later.