Midvale, UT – A high school yoga and health teacher shot her ex-husband’s girlfriend to death in front of their toddlers on Sunday.

The Salt Lake Tribune said the incident began when 32-year-old Chelsea Watrous Cook went to her ex-husband’s apartment to drop off cold medicine for one of their three-year-old twins.

Cook, a health and yoga teacher at Skyridge High School in the Alpine School District, stopped by the apartment at about 7 p.m. on Nov. 25 and went inside, while her ex-husband remained outside in the parking lot, the Daily Herald reported.

The Unified Police Department said she was asked to leave the apartment by her ex’s girlfriend, 26-year-old Lisa Williams.

Cook refused, and instead locked herself inside the bathroom while on the telephone with a 911 dispatcher, the Daily Herald reported.

Next, Unified PD said she let herself out of the bathroom, walked over to her coat, pulled out a gun, and opened fire on Williams, all with her three-year-old twins watching.

“[Cook] then suddenly pulled out a handgun and fired three to five rounds at the victim,” according to jail documents, The Salt Lake Tribune reported. “The victim fell back and landed on the couch.”

That’s when Cook’s ex-husband returned to the apartment and took the gun away from her. Then he tried to render aid to Williams.

The probable cause affidavit said that Williams had been shot twice in the torso, and died at the hospital, according to The Salt Lake Tribune.

Cook began putting on her coat to leave after she shot Williams, but her ex-husband stopped her, and held her until police arrived to take her into custody.

Police arrested Cook and took her to the Salt Lake County Jail, where she was booked on suspicion of aggravated murder, KJZZ reported.

She was being held on a $1 million bail, the Daily Herald reported.

Court records showed that Cook was charged with assault and two counts of domestic violence in the presence of children on Oct. 16, and was scheduled to appear in court on Dec. 18 for that incident when she allegedly shot Williams, Deseret News reported.

She was teaching at Skyridge High School at the time of her arrest, but school officials quickly moved to terminate her, and removed all references to the former teacher from their website, The Salt Lake Tribune reported.

Alpine School District Spokesperson Kimberly Bird confirmed that Cook had been employed by the district for four years, first at Lehi High School and then at Skyridge.

The school district sent out a letter to parents telling them what had happened and discouraging parents and students from talking to the media, while promising counseling resources would be available at the local high schools, the Daily Herald reported.