Kyle Camp, 36, is accused of engaging in sexual activity with a 12-year-old in the past month, Patch.com reported.
Officials were notified about the incident by a student who goes to Joliet West High School.
Camp was locked up at the Grundy County jail on Friday night.
Camp teaches social studies at Dirksen Junior High School in Joliet. He also coached basketball and soccer, police said.
Joliet Deputy Police Chief Al Roechner told The Herald-News: “When officers arrived at the school they learned Camp had already been removed by administration earlier that day and escorted from the grounds.”
Police spoke with the victim and then went to the school to speak with Camp, who is from Minooka. The school had already removed him from the junior high, and officers were sent to his home and took him into custody, Patch reported.
“This is still an open investigation and other charges may be pending,” Roechner said.
Camp was placed on paid administrative leave, according to Joliet Public Schools District 86.
“As soon as we heard a complaint, we immediately asked [Camp] to leave,” Joliet Public Schools District 86 spokeswoman Sandy Zalewski told the Herald-News.