An East Texas kindergarten teacher is in custody after admitting to having sex with four high school students, two of them simultaneously.

Heather Lee Robertson (KHOU-TV)

Heather Lee Robertson, 38, of Lufkin, in Angelina County, was arrested Saturday, the Lufkin Daily News reported. She resigned from Hudson ISD last Thursday.

Police were tipped off about the encounters and began questioning possible victims.

According to an arrest warrant affidavit, Robertson began "chatting and sexting" with one student via Snapchat just after spring break, then one day invited him to her apartment. When the student asked whether he could bring a friend he was hanging out with, she consented, he said.

Robertson was lying on the couch, vaping, when they arrived, the affidavit said. After chatting with them briefly, she had sex with both of them, police records say.

The two told police of others who may have been involved with Robertson, and police conducted more interviews.

Two students told police they had each had sex several times with Robertson at the apartment. She told police she would pick up the boys late at night and admitted having sex with one of them four times.

She didn't ask them to wear condoms, she told police, because she was unable to bear children. She also said she'd recently begun drinking heavily and had occasionally forgotten details about the encounters.

She also admitted asking the boys not to reveal the encounters to anyone.

According to the Daily News, Lufkin was arrested last month for driving while intoxicated. According to her Facebook page, the paper reported, she taught at Burley Primary School in Lufkin from 2000 to 2013.

If convicted, Robertson could face up to 20 years in prison.