It all started overnight when deputies say Romanus Anthony Robertson III got into a fight with his girlfriend's ex-boyfriend, identified as 34-year-old Artuiro Magee, at an apartment complex on Ella near Cypress Creek Parkway.
Robertson is accused of then shooting Magee and killing him.
Magee is pictured below.
Robertson then fled with his girlfriend, later identified as Jasmine Khalil Johnson. She also goes by Jasmine Khalil Whitmore, according to authorities.
The two took off with the two children, 9-year-old DJ and 11-month-old Kalis. According to officials, DJ is the girlfriend's son, but the baby is not her child.
An earlier report from the sheriff's office said that the children were eight years old and a year old. Authorities say DJ and Kalis, along with an 11-year-old and a 6-year-old, were inside the apartment at the time and that there is no indication that they saw the shooting.
According to authorities, Robertson was at the complex twice within the last 24 hours, and it was that second disagreement that turned deadly.
By 9:45 a.m., an Amber Alert was issued for the boy and the baby.
Just over two hours later, the children were found safe after Robertson was stopped at a business in Nacogdoches.
That's when the alert was canceled.
"[The children] were unharmed and in good health," read an update issued by the Nacogdoches Police Department. "Texas Child Protective Services are working on reuniting them with family."
Police said Robertson was arrested without incident and Johnson, who had two outstanding warrants out of Harris County for aggravated assault, was also arrested.
The 11-year-old and 6-year-old were left at the apartment with a second woman, who had been speaking with investigators.
Both Johnson and Robertson were released to deputies in Harris County, where the investigation will continue.
Follow Courtney Fischer on Facebook, Twitter and Instagram.
Follow Mycah Hatfield on Facebook, Twitter and Instagram.