(CNN) -- Police said Friday that they tracked down the mother of three children -- all apparently 3 years old or younger -- who were found alone the previous morning in a vacant building in Portland, Oregon.
Police released a brief statement about noon Friday, saying, "The mother of the missing children has been located, and we thank everyone who helped with information. We do not need need any additional tips."
Authorities did not offer any more details, including the identities of the mother and children or whether charges will be filed in the case.
The investigation began with a 911 call placed about 9:25 a.m. Thursday, about a man who'd heard children's voices apparently coming from a shed behind his house in East Portland.
Police officers arrived and found the "vacant residence" where the sounds had come from. There they talked to "a number of homeless people on the premises" and discovered the three "olive-skinned" children.
The youngest is described as a 15-pound infant who is between the age of 8 and 15 months. She has short black hair, brown eyes and two lower front teeth showing.
The next oldest child is another girl. Weighing 28 pounds, she has long black hair and brown eyes and is about 2 years old, police estimate.
The third child is a boy, approximately 3 years old. He also weighs 28 pounds and has brown eyes, as well as short black hair.
Homeless people initially told police that a woman, believed to be the children's mother, had abandoned the children there the night before.
More interviews with homeless people and calls to a tip line yielded some leads in the probe by Friday morning, though at that point police said they were still trying to identify the children, their parents or any other family members.
The three youngsters appeared to have been reasonably well-clothed and fed before they were apparently abandoned, King said.
They were all checked out medically and appear to be healthy, King said. They were placed in the care of the state Department of Human Services, he said.
A woman who lives across the street from where the children were discovered said she saw a couple of people on the property Thursday morning and called the owner to suggest he call police, The Oregonian newspaper in Portland reported.
"Little did I know they had three babies in the backyard,'' the newspaper quoted Judy Baxter as saying. "It was real sad when we saw the kids come out.''