DENVER -- A 7-year-old boy and his 8-year old sister were found safe Thursday after being reported missing by their mother.

A Denver police detective said the mother had last seen the children nearly 12 hours earlier.

Police were called to the 8700 block of 11th Avenue around 5:00 p.m., said Detective Ken Klaus.

The children were located unharmed at an auto parts store a little more than two hours later.

A friend of the children’s mother and several neighbors told 7NEWS the woman works an overnight shift.

“She saw them at 8 (a.m.) when she got in, she fell asleep and when she woke up around 4, the kids were missing,” said neighbor Tyrell Doyle.

Members of the Denver Fire Department searched a nearby drainage area for any sign of the siblings.

The pair was found after 7 p.m. at an Auto Zone store at Yosemite and Colfax Avenue. The business is a few blocks from the children’s home.

“Their grandmother actually found them,” said a woman who did not want to be identified but called herself a best friend to the children’s mother.

The woman said the kids climbed out a back window and wandered away barefoot without telling anyone.

Denver police wouldn’t confirm circumstances surrounding the children’s disappearance.

“It’s all under investigation,” said Klaus, and added the situation is, “a family matter.”

The two children and younger boy were placed in police cars.

A woman, presumed to be the children’s mother, was seen shouting at police, “Don’t take my baby.”

The woman declined to answer questions when approached by 7NEWS.

A police spokesperson would not discuss the status of the children Thursday night, and said it was too early to know if any charges will be filed.

Klaus said Denver Social Services was involved in the case.

“She’s just devastated,” the woman’s friend said of the mother.