Constable Stefan Witehira said he had just returned home to Palmerston on Monday night after working as acting sergeant in Oamaru when he received a report of a burglary at East Otago High School.
Items, including air pistols and a bow and arrow, were taken from a storage room at the school.
The sole-charge Palmerston policeman said he was alerted by a local resident, whose house was being repeatedly hit by what appeared to be pellets.
When Const Witehira arrived at Ross Reserve, a block north of the school, he spotted two people wearing hooded sweatshirts fleeing into nearby bush. He had no time to think about what might happen, and chased the pair through the bush.
"It was an interesting moment."
Catching up with them, he was surprised to discover the pair were youths, aged 13 and 14.
The unarmed officer said he was grateful the teenagers did not present the weapons, which were later recovered at the scene.
"I had no idea they had dropped the weapons until I caught up with them."
The families of the boys, who did not attend school in Palmerston, were "very upset over the behaviour of their children".
The boys have been referred to Youth Aid.
The youths' actions were incredibly dangerous and could have sparked a more serious incident, Const Witehira said.
Last month, the policeman was awarded the New Zealand Police Silver Merit award for his professionalism and courage during a February 2009 incident, where an armed fugitive shot at him and Hampden police officer Darrin Low, who was also awarded a silver merit award.
The two officers were laying road spikes when the offender fired shots at them, with the man also pointing his gun at Const Witehira during a foot pursuit on the outskirts of Palmerston.
"I've had 27 years' experience with firearms. When you have a firearm pointed directly at you, it's something you just don't forget," Const Witehira told a depositions hearing in Oamaru last year.
