CHICAGO, Ill. (WGN) — Five children were taken to hospitals after reportedly smoking a vape pen in gym class at a Chicago elementary school Wednesday.

According to the Chicago Fire Department, the children were transported to local hospitals after reportedly “smoking a substance” at Harvard Elementary School in Chicago’s Grand Crossing neighborhood just before 2 p.m. Wednesday.

A source told WGN that the students were on a field trip to Lincoln Park Zoo on Tuesday when one of them picked up a discarded vape pen and brought it to school Wednesday.

According to the Chicago Police Department, several students vaped during gym class. It’s unclear what substance the vape pen contained.

The children involved are reportedly 9 to 10 years old and are all in good condition, according to the CFD.

WGN has reached out to Chicago Public Schools for comment but has yet to hear back.