Update: Carlethia "Carlee" Nichole Russell returned home on Saturday night. She was taken to a hospital for evaluation. Read the latest coverage here.

A search is ongoing for a 25-year-old woman who went missing Thursday night after she called 911 from a highway in Hoover, Alabama, to report that she had seen a toddler walking along the side of the interstate, authorities said. A reward totalling at least $50,000 is being offered to help locate Carlethia "Carlee" Nichole Russell.

The Hoover Police Department reports that Russell, a nursing student, called 911 emergency dispatchers just after 9:30 p.m. local time Thursday and informed them that she had stopped to check on a young child that she had seen walking on the side of Interstate 459.

Police said that after speaking to 911, Russell immediately called a family member. During that call, the family member "lost contact with" Russell, "but the line remained open," Hoover Police Lt. Daniel Lowe said in a news conference Friday.

Responding officers located Russell's abandoned car along with some of her belongings nearby — including her cell phone — Lowe said, but no sign of her or a child. 

"We're currently analyzing that phone to see if there's any information on there that could help us," Lowe said. 

Russell was on her way home from work after having stopped off to pick up food, police said.  

"A single witness has reported possibly seeing gray vehicle with a light-complected male standing outside of Carlee's vehicle, but we have no further information on that individual or the vehicle at this time," Lowe disclosed.  

Talitha Russell, Carlee's mother, told reporters that her daughter was on the phone with her sister-in-law at the time that her voice dropped out.  

"She's known to be helpful and she has a big heart," Talitha Russell said of Carlee. "And she does know not to stop for anyone, even a child on the side of the road. But she did call 911. And I think she kind of let her guard down thinking they were so close. And when she got out the car, she did tell my daughter-in-law, 'I can't just leave this little child on the side of the road.'"

Hoover is part of the Birmingham metropolitan area. Lowe said a massive search was ongoing involving local, state and federal agencies. A large group of volunteers organized by Russell's parents were also assisting in the search effort. 

"We're going to be looking in every direction," Carlee's father, Carlos Russell, said. "We're just going to scour the earth."     

The police department for the Alabama city of Harpersville, which is located about 30 miles east of Hoover, reported Friday that Russell had been in Harpersville earlier in the day Thursday, "handling some business."

"We were so impressed by her respect, poise, good attitude and her drive to become a nursing student and help others," Harpersville police wrote in a statement. 

On Saturday, Hoover police released a new photo of Russell in an effort drum up more leads. Police said they have not received any calls regarding a missing child.

A reward totaling at least $50,000 has been offered for her safe return, which includes $20,000 from an anonymous source, $5,000 raised by CrimeStoppers of Metro Alabama, and $25,000 from real estate company Keller Williams, according to CBS Birmingham affiliate WIAT. 

Police describe Russell as being 5-foot-4 inches tall and between 150 to 160 pounds. She was last seen wearing a black shirt, black pants and white Nike shoes.

Anyone with information regarding Russell's whereabouts is being asked to call Hoover police at 205-444-7562.

In:
• Alabama
• Missing Woman