Updated 1/5/11 – 9:53 p.m.

PLAINFIELD, Ill. (CBS) — A suburban high school teacher was in jail Wednesday, charged with having sex with a 16-year-old student.

Ashley Blumenshine, 27, was arrested behind a Kohl’s department store in Plainfield on Tuesday. Police caught her in a car with a 16-year-old boy and determined that they’d had sex shortly before the officers arrived.

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Blumenshine’s attorney said she is innocent.

CBS 2’s Susanna Song reports that Blumenshine, who most recently lived in the 4300 block of Nutmeg Lane is Lisle, has taught dance and physical education at Plainfield North High School for four years. But her popularity might have gone too far.

“I remember she’s a really nice lady,” Plainfield North High School graduate Michael Deland said.

Around 6:30 p.m. Tuesday, a Plainfield police officer arrested Blumenshine after allegedly catching her in a car with a student outside the Kohl’s department store at 11860 S. Route 59 in Plainfield.

“The person in the back was partially unclothed,” said Plainfield Police Chief William Doster of the 16-year-old boy.

Police noticed two vehicles in the parking lot were sitting much farther out from the store than other vehicles in the lot.

On Wednesday, the Will County State’s Attorney’s office charged Blumenshine with aggravated criminal sexual abuse.

“They made certain statements to the officer that led them to believe that that’s what went on,” Doster said. He said the affair appears to have been going on for a month or so.

“Sad for the teacher, sad for the student, sad for the school, sad for the community,” said Doster.

“Our first priority is always the safety and security of our students,” said Tom Hernandez, Dir. of Community Relations for District 202.

When asked if Blumenshine would be allowed to teach while out on bond, Hernandez said, “At this point, she is not in the building.”

He says a substitute will take over Blumenshine’s classes at Plainfield North High School.

The school also provided students with counseling.

“There are certainly students who are upset by the situation,” said Hernandez.

“It’s kind of shameful to our school and, I don’t know, it’s upsetting a little bit,” Deland said.

Doster said, “Some of the students are upset about the whole thing. It does get to be a little traumatic for the students.”

Tyler Recek, who graduated from Plainfield North High School last year, said news of the arrest spread quickly around town.

“I found out just a little bit ago, but my friends found out last night over the phone, Facebook everything else,” Recek said.

CBS 2’s Kristyn Hartman reports that after Blumenshine bonded out of jail Wednesday afternoon, she covered her face. People close to her walked her to a car and helped her into the backseat before driving off.

Recent Plainfield North High School graduate Nikki Conway says, “It was like losing a friend, I guess, to some of the senior girls.”

Conway said that Blumenshine was a popular staff member, and fellow male students would often talk about her.

“No one’s going to lie, she’s really pretty,” said Conway. “It was always just a joke though, I mean, everyone flirted with her. She was always nice to all the guys, all the teachers.”

Conway said Blumenshine was also nice to all the girls.

“So it was never expected at all,” she said of the charges.