The search for a missing Texas mom and her three-week-old baby girl is still underway, and authorities said Tuesday they aren't ruling out any possible suspects.

Heidi Broussard and her daughter, Margot Carey, vanished from their home near West William Cannon and South First Street in Austin on Thursday after Broussard dropped her son off at Cowan Elementary School in the morning, police said in a news release.

Authorities believe both mother and baby returned to their residence before they went missing, but Broussard's car and her and her daughter's belongings were all still at the residence when Broussard's fiance, Shane Carey, discovered them missing and alerted police.

TEXAS MOM, 2-WEEK-OLD GIRL VANISH; BABY'S FATHER PLEADS FOR THEIR RETURN

"We have reason to believe that both of them were back at the apartment complex after being at the school," Detective Brad Herries with the Austin Police Department Violent Crimes Unit said at a news conference Tuesday.

Police said they were called to the apartment at 7:30 p.m. on Thursday. Shane told local news outlets that he received a phone call from his son's school when Broussard didn't return to pick him up at the end of the day.

The couple, who has been together for nearly 10 years, was also raising Carey's older child from a previous marriage.

Investigators said they "do not have a person of interest" currently, adding that "anything is possible" and they are not ruling out any potential suspects, Herries said.

"We're exploring every avenue we have and every possibility," he said. "It's possible that Heidi and Margot left on their own accord. It's also possible that there could be something nefarious or foul play involved."

Police alluded to previous calls of disturbances or "investigations" at the apartment prior to the mother and daughter's disappearance, but did not elaborate.

Authorities were tight-lipped on the details of the "ongoing investigation" but did say that the FBI has teamed up with the police department to aid in the search. Authorities are asking the community to call the police if they have any information that could lead to finding Broussard and her daughter.

Herries said the search for the pair is ongoing and police "have no reason to believe Margot or Heidi are harmed. We are still looking for them in a search and recovery manner."

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Broussard is 5 feet, 3 inches tall and weighs 150 pounds. She has long, dark brown hair with highlights.

Margot is a newborn who weighs 7 pounds, 7 ounces. She is 22 inches long.