A 12-year-old boy has died after being stabbed during a fight in a schoolyard on Brisbane's bayside.

Elliott Fletcher was stabbed in the chest at St Patrick's College at Shorncliffe about 8:00am AEST.

He was taken to Brisbane's Royal Children's Hospital in a serious condition but later died.

Police allege the boy was stabbed with a knife by a 13-year-old fellow student.

The 13-year-old was found nearby with minor wounds and is assisting police with their investigation. It is not clear what sparked the incident.

The school was put in lockdown this morning after the stabbing but the restrictions have now been lifted.

It is the second stabbing involving students at a Catholic boys' schools in Brisbane in the past 10 days.

But criminologist Professor Paul Wilson says it does not mean there is a trend.

"I don't think that the fact that it occurred in a Catholic school necessarily points to more problems in Catholic schools at all," he said.

"But I do think that school, and other schools where there have been serious assaults, have to be analysed very carefully."

Tributes

Scores of condolence messages have been left on a Facebook page dedicated to the dead boy.

"Devastating. A dark day for the family and all St Patrick's College Old Boys.....RIP brother," one post said.

Many more messages lamented the loss of such a young boy.

One person wrote: "soooooooooo sad 2 young to die."

"My thoughts are with his family and friends," wrote another."May you rest in peace. No child's life should end this way."

Increasing violence

The Foundation for Young Australians says there is no doubt violence is increasing amongst the nation's youth.

Today the foundation addressed a Melbourne hearing of the Federal Government's long-running inquiry into youth violence.

Its primary recommendation was that funding be increased to school-based programs targeting youth violence.

The foundation's Sharby Ibrahim says today's tragedy only highlights the need for classroom-based education about violence.

"I think what's extremely aggravating is that we've had so many of these wake-up calls," he said.

"The fact that another young person has died ... through this kind of behaviour just shouts about the fact that there needs to be action and it needs to be taken drastically.

"It's been shown that there has been a significant increase not only in the amount of violence but also in the severity of violence.

"That means more knives are involved, there have been more deaths, there are more guns involved and sometimes these attacks are perpetrated by groups of young people."