An Adelaide woman has been charged after the death of a nine-month-old boy.

Neighbours said the baby's father ran up the street, desperately looking for help after the boy was found unresponsive in the family car.

One neighbour tried to revive the baby and performed CPR until paramedics arrived.

Midlow Road in Elizabeth Downs was swarmed with emergency services before 8pm yesterday.

Police have seized CCTV to determine how long the baby was in the car.

Neighbours said the mother had told them it had not been long.

"She said the car was there for about 20 minutes," resident Joshua Hill told 9News.

Detectives have gone door to door to speak to neighbours.

The heartbreaking death has shattered residents on the street.

"A bit uneasy, especially because it's a kid and we're meant to protect them," neighbour Blair Ross said.

"I've got a three-and-a-half-year-old myself, so it was kind of hard to see," Hill said.

"I've got a grandbaby and that's just horrible," resident Jessica Edwards said.

A 31-year-old woman from the property was charged with criminal neglect.

She was bailed to face court next month.