(CNN) Police in Austin, Texas, are looking for a woman and her newborn baby who have been missing since last Thursday, and the baby's father is pleading for the public's help.

Heidi Broussard, 33, was last seen with her daughter Margot Carey, now 3 weeks old, when she dropped off another child at an elementary school about 7:30 a.m., the Austin Police Department said.

Police said they believe Broussard returned home with her baby before they both disappeared. They were reported missing to police at 7:30 p.m., officials said.

Det. Brad Herries said investigators do not have a person of interest in the case and do not yet know if there is foul play involved. The FBI is helping the investigation.

"We continue to search. We've been working continually since Thursday night to try to find Heidi and (her daughter)," Herries said.

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