SPRING, Texas -- A woman has been charged with capital murder in the shooting of a young mother and the abduction of her newborn son near Houston, a prosecutor said Wednesday.

Montgomery County District Attorney Brett Ligon told ABC's "Good Morning America" that Verna McClain was charged early Wednesday in the killing of Kala Marie Golden.

Witnesses say an argument broke out between Golden and another woman as Golden left Northwoods Pediatric Center in Spring on Tuesday afternoon with her 3-day-old son, Keegan. The woman shot Golden up to seven times and snatched the baby from her arms before driving away in a blue or light green Lexus, according to witness accounts.

Ligon said McClain's statement to investigators indicate the shooting was part of a wider plan to kidnap any child and that Golden was in the wrong place at the wrong time.

"There were statements as indicated in the arrest record that were made by Ms. McClain that led us to believe that, in fact, this was an intentional act on her part," Ligon said. "Not that Ms. Golden was targeted specifically, but that this was part of a plan to kidnap a child."

He made no mention of a man whom witnesses said they saw in the Lexus that was blood stained on the driver's side.

Keegan was found unharmed Tuesday evening. Ligon says Child Protective Services are looking after him but that they expect the baby to soon be reunited with his father.

Authorities detained a person of interest late Tuesday, but it wasn't immediately clear if that person was McClain.

Golden's mother, Linda Golden, told the AP that she had been baby-sitting another of Kala's sons when someone at the scene called her using her daughter's cellphone. She rushed to the clinic but was unable to see her daughter because paramedics were trying to save her.

"I wanted to kiss her before they put her in the ambulance," Linda Golden said.

Ligon wouldn't say where the infant was found, but he said it wasn't at a nearby apartment complex raided by officers wielding guns and riot shields Tuesday evening. Spring is about 20 miles north of Houston.

Joshua Jesson said he was at the clinic with his girlfriend when he heard gunshots. He said he saw a Lexus next to the pickup truck, then later looked back and saw the car was gone and a woman lying in the spot where the Lexus had been parked.

"I thought she just passed out. Then somebody ran in here and said, 'Somebody got shot,'" he said.

Police quickly surrounded the clinic and much of the parking lot with crime-scene tape, and yellow markers were placed next to a purse and pair of brown sandals near a red pickup truck. Spent ammunition also was nearby.

Linda Golden described her daughter as sweet-natured and kind.

"We went everywhere together and did everything together," she said.

She said she had no idea what could have sparked the slaying and abduction.

"That's the hardest she's ever fought," Linda Golden said. "She died trying to save her baby."