Police believe Skyridge High School yoga teacher Chelsea Waltrous Cook lost her Zen when she allegedly shot and killed her ex-husband’s new girlfriend in front of the former couple’s twin 3-year-olds.

Cook, 32, was arrested for the aggravated murder of Lisa Vilate Williams, her ex-husband’s 26-year-old girlfriend, after she showed up to allegedly provide cold medicine for one of her children, who were staying with their father, The Salt Lake City Tribune reports.

The ex-husband told police Cook entered his Midvale apartment shortly before 7 p.m. Sunday while he was in the parking lot, then refused repeated requests to leave. Cook allegedly locked herself in the bathroom, dialed 911, then left the bathroom and walked toward her coat.

That’s when he said cook “suddenly pulled out a handgun and fired three to five rounds in the victim,” according to the police report.

“The victim fell back and landed on the couch.”

The ex-husband retrieved the gun and attempted to help Williams as Cook lounged on a recliner with her children. Cook later attempted to leave, and the ex-husband pinned her against the wall until authorities arrived, according to the news site.

Williams suffered from at least two gunshot wounds to her torso and later died, KSTU reports.

Cook taught yoga and health classes at Skyridge, which is in the Alpine School District in suburbs of Salt Lake City.

By mid-Monday the district had already scrubbed Cook from the school’s website.

The district also issued a prepared statement to students and parents on Monday.

“This morning we learned about a situation involving one of our Skyridge teachers, Ms. Cook. She was arrested and charged with a serious crime. We know there will be information in the media regarding this incident. We want you to be aware of what we have learned, so we can help you process and provide support to any of you who may be in need,” the letter read.

“This type of news is hard to comprehend and we want you to know that teachers, counselors and your parents can help provide support in this difficult time.”

The alleged murder wasn’t the first time Cook has gotten violent around her children, according to police.

“She is also facing domestic violence charges in Herriman justice court related to an Oct. 16 incident,” the Tribune reports.

“Charging documents were sealed, so few details were available about the alleged crimes, though charging documents say she is accused of abuse in front of children. She has pleaded not guilty to two misdemeanor counts.”

Alpine School District officials alleged they were unaware of the pending domestic violence charges until this week, according to KSTU.

Court records show the ex-husband, Travis Cook, filed for divorce against Chelsea Cook in August 2017, and the divorce was finalized in December 2017.

KUTV reports Salt Lake City Police are handling the murder case because one of the parties involved in the incident is related to an employee in the Unified Police Department, which had original jurisdiction over the case.