A Texas mum who shot and killed her two daughters posted a message on Facebook in March demanding the right to keep semiautomatic handguns.

Christy Sheats, 42, got into an argument with her two daughters on Friday afternoon local time. Police say she shot and killed Taylor Sheats, 22, and Madison Sheats, 17, before being shot by police.

Police arrived at the normally quiet neighbourhood in Fulshear, west of Houston, after a series of 911 calls alerted them to the dispute.

One of the daughters died at the scene and the other was transported to a local hospital but did not survive.

Madison and Taylor Sheats who were shot and killed by their mother after an argument. Photo / Facebook
Madison and Taylor Sheats who were shot and killed by their mother after an argument. Photo / Facebook

On Facebook, Fort Ben County Sheriff's Office wrote the girls' mother refused to lower her weapon when police arrived and was shot and killed by a Fulshear officer.

Fort Ben Sheriff Troy Nehls posted an update on Saturday afternoon.

"As everyone is certainly aware, we had a terrible incident last night that involved the deaths of three people," he wrote.

"An unimaginable tragedy that it seems we see too often."

He thanked deputies and detectives for keeping the community safe and offered his prayers to the Sheats family.

The Houston Chronicle reported the girls' father was at home when the shooting took place. He was not injured but was taken to hospital in a distressed state.

"He's going through a very difficult time," Sheriff Nehls said.

In March, Christy wrote on Facebook: "It would be horribly tragic if my ability to protect myself or my family were to be taken away, but that's exactly what Democrats are determined to do by banning semiautomatic weapons."

That's right! #merica

Posted by Christy Byrd Sheats on Saturday, 9 January 2016

In January, she shared a post with the following message: "I have 10 guns. Obama wants eight of my guns. How many guns do I have? That's right, I have 10 guns."

The neighbourhood where the shooting took place was described as a "comfortable, middle class subdivision" by the Chronicle.

Christy posted a photo of herself and her two daughters in 2015. She wrote: "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."