Two teenage boys left a man with a "small stab wound" after trying to rob him of his phone in a field in Kettering.
Between 12.30pm and 1pm yesterday (Monday, January 14) the victim, a 28-year-old man, was walking across a field next to the River Ise, between Valley Walk and Deeble Road.
As he was walking towards Deeble Road, past the footbridge that crosses the river, he was approached by two teenage boys who commented on his mobile phone, which he was using at the time, and demanded he hand it over.
He refused and one of the boys then punched him in the stomach.
Both teenagers then ran off empty-handed, away from Deeble Road towards the allotments on Elizabeth Road.
A Northamptonshire Police spokeswoman said: "When the victim got home and called the police, he realised he had sustained a small stab wound to the stomach and attended hospital for treatment.
"The suspects are described as being about 14 or 15 years old and were wearing dark clothing and baseball caps. They had local accents."
Officers are appealing for information and anyone who was in the area yesterday lunchtime and witnessed the incident or believes they may have seen the suspects or have any information about them, is asked to contact police as soon as possible.
Anyone with information should call Northamptonshire Police on 101 or Crimestoppers anonymously on 0800 555111.