A student at Philadelphia’s West Oak Lane Charter School brought marijuana-laced treats to school Friday, giving them to other students, the principal said.

“Some students did take some edible marijuana this morning,” said Charletta Zeigler, the principal of the K-8 charter, who said she called police after learning of the incident from students.

The students involved were between the ages of 11 and 13, Zeigler said.

Police said the student gave laced Rice Krispies Treats to at least 15 other students around 9:50 a.m. After administrators realized what had happened, they arranged to have the students medically evaluated at the school at 7115 Stenton Ave. A police spokesperson declined to provide additional information, including whether the student would be charged, saying it was “still early in the investigation.”

Zeigler said kids had posted on social media Thursday that “it was going to happen." Students told school leaders about the posts on Friday, Zeigler said.

Students were released to their parents after being evaluated, Zeigler said. She said none of the students was sickened, but declined to discuss details of the incident, citing the ongoing investigation. “Right now, we are just making sure students are OK,” she said. “We’re fully cooperating” with police.

“It’s quite difficult” to stop something like this from happening, she said. “What we can do is continue to educate our children and parents.” The school left voice messages for parents and sent students home with a letter Friday, Zeigler said.

One of the city’s oldest charter schools, West Oak Lane opened in 1998 and enrolls more than 1,000 students.

It’s far from the only school to deal with marijuana edibles. Across the country, schools in the past year have reported incidents involving students giving marijuana gummy bears and cookies to classmates. In some cases, children have been unaware the candies contained marijuana.

In May, the Cheltenham School District told parents that students at Cedarbrook Middle School had ingested marijuana-laced edibles.

While the Philadelphia region has 20 medical marijuana dispensaries, cannabis retailers in Pennsylvania are prohibited from selling edibles.