The Armed Offenders Squad has been called to a camping site in Manakau in southern Manawatu late last night.
Police were called to the incident at the Waikawa Camping Ground, near Manakau, south of Levin at 9pm last night.
A police statement said there were reports of a disagreement between campers and that a man had a knife and was threatening others.
It was also alleged the man had fired some shots from an air rifle.
A post on social media described gunshots being heard and said a man was allegedly "threatening to stab and shoot people".
The Palmerston North Police Armed offenders Squad along with the Levin Police attended the incident and located two air rifles and a machete at the site.
A man was detained and was assisting police with their enquiry.
A police cordon was in place late last night.
Police said an ambulance on standby at the site had entered the cordon to treat a man who was injured.
He was treated for a laceration to his eye.