A Texas mum has been charged with murder after allegedly shooting her four children, killing two of them, according to local authorities.

Oninda Romelus is facing two counts of murder and two counts of  aggravated assault with a deadly weapon, as reported by Brazoria County Sheriff Bo Stallman. The children were discovered shot inside a vehicle in Angleton on Saturday.

Tragically, two of the children, aged 13 and three, succumbed to their gunshot wounds, while the other two, aged eight and nine, are now in "stable condition", stated Stallman. The 31 year old mother made a 911 call at 4:48 a.m., requesting police to come to her location, as per the Sheriff's Office. The news emerges after a teenage Nazi who plotted school shooting was locked up for 18 months.

"She gave us information that we needed to come to her location, we didn't know exactly what we were responding to at the time," Stallman revealed during a press conference on Sunday. Deputies arrived at a Shell petrol station on Highway 288 in Angleton, about 45 miles south of Houston, where Romelus had pulled over in a white Audi saloon, reports the Mirror US.

Upon arrival, deputies found the four children shot inside the car and immediately began life-saving measures until medical assistance could arrive. The two surviving children were airlifted to a hospital in the Houston area.

Romelus was subsequently arrested. "Yesterday, Brazoria County county deputies responded to an unthinkable, unimaginable tragedy. This event has shaken our community and we are all feeling the loss," Stallman said.

"We believe that the evidence shows that this tragedy has occurred inside the vehicle and that Romelus, the mother of the children, is the shooter," the Sheriff stated. He added: "It is impossible to make sense of a senseless tragedy like this, but we will do everything we can to seek justice for these children."

Romelus, a resident of Montgomery County north of Houston, is currently under investigation with evidence being collected from her home.

The grandfather of two of the victims has given an emotional statement about his reaction to the tragic event. James Chappell, hailing from Georgia, told KPRC 2 that his eight year old grandson, who is in hospital, and his three year old granddaughter, who tragically lost her life, were involved in the incident.

In memory of his granddaughter, he said: "She had a beautiful smile, just like her dad."

He expressed his shock upon hearing about the shooting.

"I started crying immediately. That's my grandbaby," Chappell added. He revealed that his son, the father of the two children, is currently behind bars.

Romelus is being detained in Brazoria County Jail on a $14 million bond. The authorities have yet to disclose any details regarding a potential motive for the shooting and it remains unclear where exactly the incident took place.

The two surviving children have been interviewed by deputies, according to Stallman. He noted that the investigation is ongoing and there is a lot of information that is "not able to be released at this point."