A Texas mother faces first-degree felony charges in the deaths of her 2-year-old daughter and 1-year-old son after police say she locked them inside a sweltering car last month to teach them a lesson.

Cynthia Marie Randolph, 24, was arrested Friday on two counts of causing injury to a child. Authorities later determined that the children died from extreme heat exposure.

The incident happened on May 26, when Randolph’s 2-year-old daughter, Juliet, and 1-year-old son, Cavanaugh, were found dead in a locked car in the driveway of her home outside of Fort Worth, police said.

Cynthia Randolph was arrested in connection with the deaths of her two children from extreme heat exposure after they were found locked inside a car on May 26, 2017. Parker County Sheriff's Office

Temperatures hovered around 96 degrees that day, reported NBC Dallas-Fort Worth.

In documents released Friday, the Parker County Sheriff's Department used Randolph's alleged shifting statements about how her children died as probable cause to charge her.

Authorities said Randolph initially told officers that she had been folding laundry in the house while her children played outside. When she didn’t hear from them for nearly half an hour, Randolph said she searched for the toddlers before discovering them locked inside the car, alongside her keys and cellphone.

She then told officers that she had to break a window and rescue the children, then called 911, authorities said.

But when she was arrested Friday, police said Randolph admitted to officers that she locked the children inside the car on purpose.

"When they refused to leave the car, the defendant said she shut the door to teach Juliet a lesson, thinking she could get herself and her brother out of the car when ready," authorities said in the probable cause affidavit.

It added that Randolph told officers that she went inside the home, smoked marijuana and fell asleep for several hours.

"When she woke, the defendant found her children in her vehicle, unresponsive," authorities added. "The defendant said that she broke the car window to make it look like an accident."

Randolph was booked into the Parker County Jail. A bond had not been set and it wasn't immediately clear whether she retained an attorney, NBC Dallas-Fort Worth reported.

So far this year, 13 children have died from heat strokes after being left in hot cars, according to San Jose State University professor Jan Null. Null, who is a meteorologist that works with the National Safety Council, maintains a website that tracks trends in hot car deaths each year.

According to her research, an average 37 children die in hot cars annually in the United States.

In an effort to combat the rise in hot car deaths, Rep. Tim Ryan, D-Ohio, introduced the Hot Cars Act of 2017. If passed, the legislation would require new cars to come equipped with a system for alerting the driver if a child is left in the back seat after the car is turned off.