A 12-year-old boy died Monday morning after he was hit by a girl during morning recess at a Laurentians-area school north of Montreal, police said.

Provincial police said the children were arguing in the schoolyard in Saint-Eustache and insulting each other when the quarrel escalated into a shoving match.

The 11-year-old girl allegedly punched the boy in the chest. The boy, who was in Grade 6, then collapsed, according to eyewitness reports.

He was taken to hospital unconscious and died later. The girl has been placed in the care of youth protection officials.

Officials at the Horizon-Soleil school said that neither of the two students had a history of violence, but noted that the boy who died was known by staff to have cardiac problems stemming from heart arrhythmia, or an irregular heartbeat.

Still, the boy was reportedly healthy enough to participate in gym class.

Police were interviewing students and staff at the school Monday.

'Isolated quarrel'

"It was an isolated quarrel," said Normand Brulotte, a spokesman for Saint-Eustache police northwest of Montreal.

"One of the two people fell down and school staff intervened to give first aid. Police and ambulance authorities were called. When they got there, he was unconscious."

Brulotte couldn't say what sparked the squabble.

The mother of three children who attend Horizon-Soleil said she was upset to learn that even after the fatal incident classes resumed.

Teachers and a school psychologist reportedly told the children about the death at the end of the day.

The principal of Horizon-Soleil, Christiane Rainville, sent home letters informing parents that a child had died.

"The school is deeply distressed by this dramatic situation," Rainville wrote in the letter, which was also posted on the school board's website.

With files from the Canadian Press