MIAMI -- Miami-Dade police are investigating the death of a 6-month-old boy in the 1300 block of Northwest 77th Terrace.

A woman, who neighbors said is the boy's aunt, was talking with investigators at the scene but was reluctant to talk on camera.

Police said they got a call Tuesday afternoon that the infant was having trouble breathing.

"That infant, I understand, was carried over to another residence where the call was made," said Detective Roy Rutland of the Miami-Dade Police department. "Shortly after that, Miami-Dade Fire Rescue responded and transported the infant to a nearby hospital, where that infant later died."

Police said paramedics found another child, 3, who also needed to be rushed to the hospital. Detectives would not say why he needed medical attention, only that he was in stable condition on Wednesday morning.

The children's mother's boyfriend, who was watching the children at the time, was questioned by police and released on Wednesday. The children's mother, who, according to the Department of Children and Families, lost custody of one other child in the past, was not home when the incident happened.

The medical examiner's office will determine what caused the baby's death.

The mother has two other children. One of the kids was at a friend's house at the time, and another is being cared for by Child Protective Services because of an existing medical condition.