The boy, who was wearing a gray sweater and brown pants, was not harmed, but emergency responders said they were not able to wake him and transported him to the hospital.
Police said they made multiple attempts to reach his mother but were not successful and called the Department of Children and Families.
“He is currently with his mother and family, and we will continue working with the family throughout the investigation,’’ said Isaksen, who said the mother picked up the child at the hospital.
Isaksen said the department is trying to determine whether there are support services that could assist the family.
Police, who have not released the identity of the boy or his mother, said they are planning to bring her to court on charges of child endangerment and abandonment of a child under age 10.
Nuestra Comunidad, which manages the newly constructed Thomas I. Atkins Apartments where the boy‘s family lives, said private security officers responded within minutes after Boston police arrived at the scene.
David Price, the executive director, said that the boy was found unconscious and that initially no one knew where he lived. Once the identity was known, Price said, the building’s management opened his apartment door, but Price would not say whether the mother was home.
“We are cooperating fully with the police to get to the bottom of this,’’ said Price.
At the apartment building, relatives and a friend described the woman as a good mother who would never neglect or do anything to endanger her children. In addition to the boy, she has a daughter, who is about 7.
Two women who said they were cousins of the mother entered her apartment yesterday and left with a white garbage bag full of clothing.
One said the mother is unsure how the child got out of the apartment and has surmised that he might have been sleepwalking, which he had apparently done before.
“She’s a good mother, a good parent,’’ said one of the women. “She was home the whole time. He was sleepwalking. He could have easily pushed the door handle and unlocked it.’’
Freddy Oliveira, a neighbor, said the mother dotes on her children and takes morning classes to get her GED.
He described the boy as a curious, “cool kid,’’ who probably opened the front door to ease boredom.
“Sometimes you can’t control what your kids do,’’ he said yesterday. “From what I heard, she laid him down and then went to bed. He must have somehow got out.’’
A woman who also did not want to be named said she has been in touch with the mother, who is distraught over the sudden, negative attention.
“She’s feeling upset right now,’’ the woman said. “She takes care of her kids.’’
Meghan Irons can be reached at mirons@globe.com. Follow her on Twitter @meghanirons.
