The Texas mother who gunned down her two daughters before being shot dead by a police officer last week lived for her children and showed no signs of trouble before the tragedy, her friend said Monday.

Christy Sheats, 42, loved talking about her daughters, Taylor Sheats, 22, and Madison Sheats, 17, and showing her pals their photos, friend Catherine Knowles told TIME. “This woman loved her children. That was her life purpose. That was her pride. That was her joy,” said Knowles, 53, of Huntsville, Ala. “Christy wasn’t crazy. I don’t know what could have made her snap. To do this, it’s insanity. The whole thing.”

It finally stopped raining in Houston! #sunshine #happygirl Posted by Christy Byrd Sheats on Friday, April 22, 2016

Happy Daughter's Day to my two amazing, sweet, kind, beautiful, intelligent girls. I love and treasure you both more than you could ever possibly know. Posted by Christy Byrd Sheats on Friday, September 25, 2015

Authorities are investigating the mother of two’s motive and looking into whether a family dispute or a history of mental illness may have contributed to the fatal shooting. Fort Bend County Sheriff spokeswoman Caitilin Espinosa told People that police had been called to Christy Sheats’ home over a “mental crisis,” although additional details were not disclosed.

On Friday, police responded to 911 calls about shots being fired shortly after 5 p.m. to find the two daughters lying in the street. An officer shot and killed Christy Sheats after she refused to drop her weapon, authorities said.

Knowles said she was “caught off guard” after hearing the news about her friend, whom she met last summer in Huntsville, where Christy Sheats had been looking into a real estate investment. The two clicked instantly, and within an hour of meeting, Christy Sheats was already showing her new friend pictures in her phone of her two daughters, according to Knowles.

“She loved God. She loved her kids. I don’t get it. I don’t get it at all,” Knowles said, adding that the two never got “deeply personal” about their lives. “I visualize this and I think this just can’t be. I have no clue what goes on behind closed doors. This totally shocked me.”

Christy Sheats’ husband, Jason Sheats, was home during the shooting and was taken away by paramedics, CNN reports. He could not be immediately reached for comment Monday.

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