Miami police arrested a woman after her 3-year-old son was found wandering the streets.
Janisleidy Herbello, 24, was charged with one count of child neglect.
A passerby spotted the child walking alone at Northwest 32nd Place and Flagler Street about 4:15 a.m. Wednesday and called police.
"Immediately, we began knocking on neighbors' doors," said Willie Moreno, a Miami police spokesman.
"I was dropping my wife off from work and I saw an officer with a child," said David Obregon, who lives nearby. "He was calm and was not crying. He was fine."
Herbello told detectives that she had left her son sleeping at 1 am, then went to a friend's house to drink and smoke marijuana.
"She didn't see any concerns with leaving the child as he was sleeping alone," said Moreno. "This child could have been struck, could have been killed. He could have just stopped in the middle of the street. That's the worst thing that could have happened."
Police were already at Herbello's house when she returned at 5 am.
Local 10 found that Herbello has an extensive traffic violation record, including a criminal traffic citation for driving with a suspended license.
The Department of Children and Families is investigating. Officials said the department has no previous history with the mother.
The boy was reunited with his father late Wednesday morning.