A missing 15-year-old boy who often camped in a tent near his high school was found dead Friday morning by classmates in Belleville, Ont., as bitterly cold temperatures gripped the region.

"It was a group of students that did locate the body (of Tyler Little)," Belleville police Sgt. Beth Harder said Friday.

After the grim discovery, police locked down the eastern Ontario high school and launched an official probe into the death.

Little had been missing since Tuesday and police began searching for the boy on Thursday at around 10:30 p.m. after the boy's parents reported him missing. A relative told CTV Toronto that Tyler had been in a fight at school.

The family thought he had gone to a friend's house.

"Tyler didn't run away from home. It's just a a very tragic accident that's happened," said Terry Little, the teen's grandfather. "I can tell you he was a typical teenager and he was loved by all his family."

Searching through the wooded area near Moira Secondary School, officers quickly located the tent and found some of Little's personal items.

But after about three hours, the search had to be suspended for the night.

"We did the search as best that we could, given the circumstances, and we called it off at about 1:30 to wait until daylight," said Belleville police Sgt. Beth Harder. "We hadn't even been able to confirm that he was even there."

On Friday, as officers were preparing to launch a full ground search of the area, Little's classmates made the discovery.

"This wooded area is familiar to the students, so they know the area very well," Harder said. "We were just preparing for the secondary ground search when we received the information that he had been found."

Shortly after the body was found, six students were spotted walking out of the forest, where they spoke with a group of police stationed in a snow-covered area.

The youths appeared to be shaken and said very little before a black SUV took them away from the scene.

Harder didn't speculate on the cause of death but she said that an autopsy is scheduled for Sunday in Toronto.

With files from The Canadian Press