An 18-year-old high school student from the Ottawa area has succumbed to injuries he suffered from an explosion in his auto-shop class on Thursday morning.

Eric Leighton died in hospital hours after the blast. He had been in critical condition after paramedics found him at the site.

The incident is being investigated by the Ottawa Police Service and the city's fire services.

Once word of his death spread, students gathered to mourn Leighton outside Mother Teresa Catholic High School, where the explosion occurred. They described him as a popular Grade 12 student and an athlete who played lacrosse and hockey.

Paramedics spokesman J.P. Trottier said Leighton was not breathing and had no pulse when emergency workers arrived at the scene. But they managed to resuscitate him by the time he arrived in hospital.

Five other people, including a male teacher, were taken to hospital because of minor injuries and fears they could have suffered concussions in the explosion. All five were subsequently released.

The school was evacuated after the blast, which occurred at around 10:40 a.m. Thursday morning, rattling desks in nearby classrooms.

Around a dozen students and a teacher were in the auto shop at the time, according to Const. Marc Soucy, a spokesperson with Ottawa police.

Vapours from an empty oil drum may have ignited, causing the explosion, Soucy told reporters. Investigators were trying to confirm whether the drum had held peppermint oil or another substance.

CTV Ottawa's Joanne Schnurr said the students were working on a barbecue-related project when the explosion occurred.

"They were working with some sort of flame I believe, and there was a 45-gallon drum of peppermint oil nearby," Schnurr told CTV News Channel on Thursday afternoon.

"It's believed that fumes from that drum ignited and caused a flash explosion."

Chris Ventura, a 14-year-old student at the school, said the explosion made a loud boom and shook desks in his classroom. Students were hurried out of the building to another high school in the area, he said.

Students were shocked by the blast, Ventura said, and there was a prevailing feeling that anyone at the school could have been seriously injured in the incident.

A note posted on the Mother Teresa website on Thursday said the "school has been evacuated" to a nearby high school in the wake of the explosion.

Schnurr said it is "quite chaotic" at the school where the students have been moved to, with frantic parents wanting to find out if their children are okay.

The school board has dispatched its "serious incident team" to the scene and counsellors have been made available for staff and students.

The explosion didn't cause a fire or produce any obvious structural damage to the building, according to Marc Messier, a spokesperson with Ottawa Fire Services.

The high school is located in the Ottawa suburb of Barrhaven, in a quiet residential area, and has 1,480 students and 130 staff.

It was cordoned off with yellow police tape Thursday morning as emergency workers investigated the incident.

Soucy said the arson squad was on the scene, which is standard practice in the case of an explosion.

He also praised the school's handling of the incident, saying that they "knew what to do and did it very well."

But Leah Glover, the parent of a student at the school, said the ordeal was "very scary" because she wasn't told anything by school officials.

"If my boys didn't have cell phones I wouldn't know what was going on," she said.

With a report from CTV Ottawa's John Hua and Melissa Lamb, and files from The Canadian Press