Authorities in Illinois are searching for a pregnant U.S. postal worker who is missing in South Chicago.

The woman, Kierra Coles, 27, was last seen on Oct. 2 near her apartment in the Chatham neighborhood, according to the Chicago Police Department. The circumstances of her disappearance have her family gravely concerned for her safety.

“I’m too scared to feel anything,” Coles’ mother, Karen Phillips, told Chicago’s WMAQ-TV. “I don’t want to fear the worst.”

A neighbor’s surveillance camera captured Coles walking toward her vehicle on the day of her disappearance. Instead of getting inside it, police said, she turned and walked away.

Dan Perkins, who is dating Phillips, told WGN-TV in Chicago he believes Coles saw “something that made her turn around that fast and cross the street.”

Coles, who is three months pregnant, was dressed in her U.S. Postal Service uniform at the time her disappearance. A spokesperson for the USPS told WGN-TV she called in sick to work that day. It’s unclear if that call was placed before or after she was last seen.

What happened to Coles after she walked away from her apartment is unknown. Her family reported her missing on Oct. 4.

Phillips told WMAQ-TV that authorities found Coles’ purse and cellphone inside her vehicle, which was still parked on the street outside her apartment. Searches of the area have failed to turn up additional leads, police said.

Coles’ older sister, Kimberly Phillips, told Chicago’s WBBM Newsradio that Coles is a responsible adult who’s excited about giving birth to her first child.

“It’s not like she’s on drugs,” Kimberly Phillips said. “She worked her butt off.”

Authorities have not yet said whether they have interviewed the father of Coles’ child.

The National Association of Letter Carriers is offering a $3,500 reward for information in the case.

Karen Phillips told WMAQ-TV her daughter has never gone more than a day without talking to her.

“It’s just sickening to wake up and not hear nothing,” Karen Phillips said. “It’s just not like her.”

Coles is described as 5 feet, 4 inches tall and 125 pounds. She has a tattoo of a heart on her right hand and the phrase “Lucky Libra” tattooed on her back.

Her father, Joseph Coles, traveled to Chicago from Racine, Wisconsin, on Tuesday.

“If anybody knows anything, please call in, let us know,” he told Chicago’s WLS-TV. “We love her [and] we miss her.”

Anyone with information is asked to contact the Chicago Police Special Victims Unit at 312-747-8274 or 1-800-UTELLUS.