WASHINGTON – A one-time, teacher-of-the-year spent weeks preparing for the first day of classes at Wilde Lake High School in Columbia. But the 31-year-old woman never showed up when classes resumed on Tuesday.

Laura Wallen, 31, who is four months pregnant, was last heard from Sunday. According to NBC Washington, her family received a “troubling” text message from Wallen.

Subsequent attempts to reach Wallen have failed and police are asking for the public’s help to locate her.

Paul Starks, spokesman for Montgomery County police, said Wallen is close with her family and gave them no notice and left no notes to indicate why she left or where she might have gone.

A group of detectives has been assigned to the case. Police and her family are concerned about her “emotional and physical welfare,” according to police.

Wallen’s sister said that the missing teacher was excited about her pregnancy, Starks said. And relatives told NBC Washington that Wallen had posted sonogram images on her refrigerator.

Wallen has blond hair and blue eyes, stands about 5-feet-5 and weighs 200 pounds. She may be driving a black, 2011 Ford Escape, has Maryland tags with the plate number M522473.

Anyone with information about the whereabouts of Wallen or her car should call police at 301-279-8000.

WTOP’s Amanda Iacone contributed to this report.