CHICAGO -- Chicago Police issued an Amber Alert Monday afternoon for three children and their alleged abductor after the children’s mother was found slain Monday in the Humboldt Park neighborhood.

Images: Mother Slain, Children Missing Video: Watch Kim Vatis' Monday Morning Report Video: Watch Rob Staffords Monday 10 PM Report

Sophia Garcia, 30, was found dead, with a plastic bag over her head, in her home in the 1700 block of North Harding Avenue, according to the Cook County Medical Examiner’s office.

Police News Affairs Officer JoAnn Taylor said the woman was found at about noon on Monday.

NBC5's Kim Vatis reported Tuesday that relatives, concerned after not hearing from Garcia over the weekend, went to the Humboldt Park apartment and found the woman's body, but no sign of her three children.

An amber alert was issued for the children, who have not been seen since Friday.

Vatis confirmed Monday that police were investigation Sophia Garcia's death as a homicide.

NBC5's Rob Stafford reported Monday night that authorities said they believe the children were abducted on Friday outside their school, but the children's relatives were not aware of it until Monday.

The three children-- Oscar Casanova, 6, Karla Casanova, 7, and Fernando Casanova, 11--were abducted from Yates Elementary School at 1839 N. Richmond St. Friday about 2:30 p.m., according to the Amber Alert. They were released from school before they were abducted, police News Affairs Officer John Mirabelli said.

Oscar is 4 feet tall and weighs 60 pounds, with dark brown hair and brown eyes. Karla is 4-foot-1 and weighs 75 pounds, with brown hair and brown eyes. Fernando Casanova is 5 feet tall and weighs 130 pounds, with brown hair and brown eyes -- all three are described as white Hispanic, the alert said.

Police are also searching for Benito O. Casanova, the suspected abductor, who is described as Garcia’s husband or boyfriend. A Grand Central Area detective said they have not yet been able to determine if Garcia was married to or just dating Benito Casanova. Mirabelli said that the suspect is the father of two of the missing children. Benito Casanova is described as a 32-year-old white Hispanic male, 6-foot-1, 230 pounds, with brown hair and brown eyes, the alert said.

Police are also searching for a silver or gray 2002 Dodge Dakota with Illinois license plate number 86196HB. One of the SUV's plates is missing.

Concerned residents said they feared for the children's safety, NBC5's Rob Stafford reported.

"They must be scared," said Martia Ortiz. "They're wondering where's their mother, why is their dad having them running back and forth who knows where? What situation (are they in)? Are they eating?"

Stafford reported they were looking for Casanova, as were neighbors.

"If the dad did do this, do something with the kids," said another neighbor, Wanda Shackleford. "Let anybody know that the kids are OK. That's the only concern that I can think of as a mother."

Anyone with information should call 911 and advise they have an Amber Alert report.

Additional information provided by Sun-Times News Group