A US woman allegedly smothered her toddler to death then sent a video of the boy's lifeless body to his father, in a jealous, vengeful rage during a text argument.

Christian Clark, 21, of McKeesport, Pennsylvania was jailed without bond after being arraigned on charges of criminal homicide in the death of 17-month-old Andre Price III and attempted homicide of his two-year-old sister Angel on Tuesday.

Allegheny County homicide detectives claim Clark was arguing with the boy's father Andre Price Jr in a text message fight that lasted more than two hours, beginning about 9pm and which becoming increasingly violent.

View photos Christian Clark, of McKeesport, Pennsylvania, was charged with criminal homicide in the death of her 17-month-old son after she sent a video of the boy's lifeless body to his father in a jealous, rage during a text-message argument. Picture: Allegheny County Police Department via AP More

The woman said she was upset about having to clean up toilet water the children spilled, but mostly because Price had left for work earlier in the day and Clark believed he planned to have sex with another woman, according to the criminal complaint.

"Ya kids ain't safe here I don't want them here" and "Answer me or im going to jail for child endangerment" were two of the dozens of texts listed in the criminal complaint.

Then came a message at 10.01pm that said, "I'm killing them" — followed by a laughing emoji with tears coming from its eyes, police said.

At various points, Clark also texted photos of each child — including one of the boy face-down on an air mattress with his face in a comforter.

View photos The woman has been jailed for the death of 17-month-old Andre Price III and attempted homicide of his two-year-old sister, Angel. Picture: Facebook More

By 10.14pm, Clark sent the first video, showing the children lying face-down while narrating, "Ahh look Angel is still alive and sweating your son on the other hand is not even breathing, I wish I could keep the camera still."

Another video five minutes later showed Clark grabbing Angel's head, prompting the girl to cry. When Clark grabbed the boy's head, he didn't respond, police said.

"First of all she is clearly fine, because watch, see she is not dead. Him on the other hand, he doesn't budge. So you might want to call the ambulance," Clark said in the video.

A minute later she texted, "All cus you wanted to go (have sex with) her & come here when you like."

At 10.23pm Clark acknowledged she was responsible for the boy's death — and police say she later admitted smothering the boy by holding him face-down on the air mattress for about a minute.

"Im sure it'll hurt me one im sitting in jail & you got all the evidence you need to I can't even say he suffocated in his sleep or say idk what happened," Clark texted.

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