A 16-year-old boy has admitted he was involved in one of a spate of hoax 911 calls that have resulted in more than two dozen lockdowns at Ottawa schools in the past month.

The call from a payphone at De La Salle High School around 10:30 a.m. Thursday reported a gunman at the school, and turned out to be false, said an Ottawa police news release.

Const. Alain Boucher said the teen was identified by tips from students after police traced the call.

In lieu of charges, the boy will take part in an Ottawa police pre-charge diversion program under the Youth Criminal Justice Act and will also face sanctions from the eastern Ontario French school board, police said. 

He is the third teenage boy to be taken into police custody in relation to hoax 911 calls about schools.

Police have released without charges a suspect they arrested Monday morning after a hoax 911 call was made about a gun threat. That call resulted in lockdowns at three east-end Ottawa high schools on Monday, police said.

Those three lockdowns and four others at high schools Monday afternoon followed a Friday news conference at which police announced the arrest of a 15-year-old boy and called for help from the public.

The boy arrested Friday morning was charged with mischief Saturday in relation to a false 911 call at Hillcrest High School on Oct. 10, according to an Ottawa police news release issued Saturday. The boy, whose name cannot be published under the provisions of the Youth Criminal Justice Act, has also been charged with two counts of failing to comply with judicial release.

Police are still investigating hoax calls about gunmen on school property that have led to other school lockdowns.

At the Friday news conference, police said they are still trying to trace 18 hoax calls they had received since Sept. 21. Most were made from cellphones, some of which are now inactive, while the rest came from payphones within the nine schools involved, police said.

Police Supt. Charles Bordeleau said Friday that police have never seen so many such incidents in such a condensed period of time.

School board officials and police said the lockdowns have caused significant fear and frustration for everyone involved.