He next heard a panicked secretary at Racette Junior High School announce over the intercom that the building was in lockdown mode. All the teens in his gym class ran for the girls' change room and hid in the corner of the showers.
"I was thinking, 'Oh my gosh, I hope everyone's all right and everyone's safe.'"
Only later did Chamberland realize the chaos Thursday morning was caused by a minivan that had crashed through an outside wall and into a classroom.
Mounties said three students were pinned under the van at the Catholic school in St. Paul. They were airlifted to a hospital in Edmonton, 200 kilometres to the west, with critical injuries.
Health officials said one of the wounded is an 11-year-old girl. Five others were transported by ambulance to the local hospital, but they were released later in the day.
Parent Michelle de Moissac said her 13-year-old daughter sent her a text message at about 9:30 a.m., saying there had been a crash and the school was locked down.
Confused, de Moissac rushed to the school and saw a giant hole in the side of the building. There were ambulance, police and fire crews and a line up of school buses.
She said a teacher told her the van had been driving erratically. It nearly hit a pedestrian a few blocks away before it went down an alley by the school, veered off the road, smashed through a chain-link fence and then went through the building, she said.
The van dove down into the classroom, which sits below ground. There were about 15 students in the Grade 6 French class at the time, de Moissac said.
"Everyone was being taken out by ambulance."
RCMP said the van's driver, a 46-year-old man from St. Paul, received minor injuries and was taken into custody. Photos from the scene show him being led away in handcuffs.
Spokeswoman Doris Stapleton said investigators are trying to determine the cause of the crash, which could include impairment by drugs or alcohol, mechanical failure, slippery road conditions and the driver's medical health.
"The results of this ongoing investigation will determine when and if charges are applicable."
De Moissac said she quickly found her son and daughter at the school and was relieved they weren't hurt. But her son is worried about some of his good buddies who were sitting in the classroom that was hit. She's also concerned for the parents of the injured children.
"For about 10 minutes I didn't know where my son was and I was freaking right out ... It's nothing compared to what these parents are going through."
School board superintendent Glen Brodziak said the school was evacuated and students were bused to three locations in the community.
"Division staff immediately started contacting parents to advise them of their child’s whereabouts and that they were safe," he said.
But Chamberland said he and the other students in his first-period gym class spent 90 minutes hiding in the change room before a teacher came to get them.
"They evacuated all the other students to the regional high school and we were still there ... They forgot us.
"We didn't know what was going on at all."
He said the group had been playing floor hockey and were wearing gym clothes so they didn't have cellphones with them. Some of the girls in the group had phones, he said, but they weren't using them. They were too upset, crying and worried about their younger siblings in the school.
Chamberland said the teacher who finally found them was his mother, Jocelyne. When she walked into the change room, she looked upset and had tears in her eyes, he said.
She quickly gave him a big hug.
Brodziak said counsellors will be made available to "any who are struggling to cope with the accident and its aftermath."
He said Racette School would be closed Friday as officials assess "if and when it is safe to return."
— By Chris Purdy in Edmonton
Note to readers: CORRECTS direction in para five