A Montreal-area mother is warning other parents to talk to their kids after her daughter and two other elementary school students were hospitalized after eating drug-laced candy they found on the floor of their school bus this week.

The three young students, ages six and seven, are in Grade 1 at Franklin Hill Elementary School in the off-island suburb of Repentigny.

"It's very scary what I went through. It was awful to see her like that," said Alexa Pando, whose six-year-old daughter, Zarah, ate the candy.

"I saw her not feeling good -- she cried and cried, and I said 'Zarah, what's wrong?'" Pando told CTV News in an interview Wednesday.

"She says 'Mommy, I don’t feel good and I have voices in my head.'"

The girl at first didn't want to admit what had happened, but finally she told her mother that she had eaten a mystery candy on her school bus. She found a bag of the gummy candy and shared it with two friends, she said.

Her symptoms were serious enough that her mother called an ambulance, and once at the hospital, two other children arrived who had ridden the same school bus, Pando explained. 

Zarah spent the night in hospital and is now back at home, feeling fine. But it was a very troubling experience not just for her family, but also for her, she said. 

"It was like, really scary, because I never felt like that before, and voices in my head -- I didn’t like it," the girl told CTV News.

Franklin Hill's principal confirmed what had happened in a letter to parents on Tuesday alleging the students consumed candy that contained cannabis.

"Yesterday, on one of our after-school bus rides, three students consumed candy containing cannabis and, as a result, had to be hospitalized," the school's principal, Peter Papadeas, wrote in the letter, which the Sir Wilfrid Laurier School Board provided.

"Students found this candy lying on the floor of the school bus and consumed it. Parents of the students on the bus were immediately contacted after we were notified of the situation."

The school and school board are working with local police to investigate the situation, Papadeas wrote.

"At this time, we do not know how the candy got on the bus," he said, noting that "police confirmed this was an isolated incident."

Edibles are legal in Quebec, but it's not legal to sell them as candy, because of exactly this risk -- that children may unknowingly eat them.

Repentigny police said they can't be absolutely sure the drug in the candy was cannabis, and that it's impossible to do an analysis because none of the candies are left.

However, spokesperson Bruno Marier confirmed that the emergency doctor who examined the children "assessed that the children's symptoms could be due to some drug consumption via candy."

Police are now focusing on discovering how the illegal candies got onto the bus, said Marier.

"We started an investigation trying to figure out what happened on the bus -- what was the trajectory of bus before Franklin Hill School?" he said.

"Maybe it went to a high school taking kids home."

Marier said it's important for kids to learn never to eat candies or other items without knowing where they're from, and to be taught to give the bag to the school driver in a case like this.

The school board didn't confirm more details about the bus in question, and how many age groups or schools it serves.

The school said it's still taking "precautionary measures" and beginning a series of awareness campaigns to teach students not to eat anything "that does not belong to them" or whose origin is unknown.

That will involve specialized teams speaking to students about the risks involved, as well as training staff to speak to students about the same issue.

Together with local public health authorities, they will also begin "age-appropriate prevention measures about drugs," Papadeas wrote.

The board and school say they are also putting together tools and online resources to help parents educate their children about drug risks.

Pando urged other parents to have a talk with their children to tell them to not eat any mysterious products.

"Just talk to them," she pleaded.