LEWISBURG, Pa. – Police contend teacher’s aide Chelsea Lorson was on the job at Lewisberg Area High School only 18 days before she sexually assaulted two students.

Lorson, 25, knowingly had sex with the teens – one boy was younger than 18, and the other, a relative, was under 16 years old – despite the fact that she knew she was infected with two sexually transmitted diseases, the Daily Item reports.

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Lorson started as a teacher’s aide at Lewisberg Area High School Jan. 13, and had direct contact and supervision over one of her accusers as part of a work-study program. She reportedly cultivated a relationship with the student and his younger relative through Facebook messaging, police said.

On Jan. 20, the victims allege she invited herself to the older boy’s house and had sex in her Jeep in his driveway, one of multiple after school, off campus romps in recent weeks.

“Eighteen days,” Central Susquehanna Intermediate Union chief academic officer Amy Morton said of the time Lorson was on the job before allegedly taking advantage of her position. “We’re astounded, quite frankly.”

“This was a devastating blow to the CSIU to know we had an employee who was part of creating a problem rather than being part of solving a problem,” Morton said.

District officials said Lorson passed all background checks and was an “exemplary employee” until her arrest. She previously worked at Montandon Elementary before her assignment to the high school.

“We have no indications other minors were involved,” Buffalo Valley Regional Police Chief Paul Yost said Thursday.

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Police contend Lorson called herself the “side chick” of the eldest victim in bragging to an acquaintance at a local department store Feb. 5. She said the two were having sex, and that she was infected with a pair sexually transmitted diseases, though it’s unclear which diseases, The Daily Item reports.

According to the Associated Press, “Police say she assaulted the minors and knowingly had transmitted sexually transmitted diseases.”

Lorson also allegedly told the acquaintance – a mandatory child abuse reporter – that she had sex with the student’s younger relative as a birthday present. Both teens were reportedly with Lorson at the store during the conversation.

The acquaintance called the state’s 24-hour child abuse tip line the next day, and Union County Children and Youth contacted police and school officials. CSIU immediately placed Lorson on paid leave.

“We are deeply upset and troubled by these allegations,” superintendent Mark DiRocco said, according to . “First and foremost, we want our kids to be safe in our schools.”

Parents, of course, are concerned.

“We are putting our most-loved possession in their hands and this is ripping my heart out that this is going on and people are starting to think this is normal,” parent June Hackenberg told the news site. “This is not normal.”

Parent Nathan Knauer agrees.

“I’m losing a lot of trust,” he said. “It’s really hard to keep any trust anymore.”

Lorson refused to speak to the police.

She was arrested and charged Wednesday with numerous felonies including involuntary deviate sexual intercourse, statutory sexual assault, institutional sexual assault, corruption of minors and recklessly endangering another person.

District officials held a community meeting with parents in the school cafeteria this week to address their concerns and answer questions about the situation.