Police investigating unexplained infant death at Adelaide motel

Police attended the Tollgate Motel after an unexplained infant death was reported. (ABC News: Briana Fiore)

South Australian Police have attended the Tollgate Motel in Glen Osmond on Saturday morning to investigate a reported infant death.

ABC News understands police and ambulances were called to the Tollgate Motel, adjacent to the South Eastern Freeway, five kilometres south-east of the Adelaide CBD, before 10:30am.

Some witnesses estimated around 20 officers were present.

Police vehicles attended the scene throughout the morning. (Supplied)

"There were at least four of five police cars here," a nearby resident told the ABC.

"It's a bit concerning that we've got police cars down the end of our quiet cul-de-sac."

Police left the scene by mid-afternoon, after establishing a cordon.

Police have cordoned off a room at the Tollgate Motel. (ABC News: Briana Fiore)

The cause of the child's death is currently undetermined.

In a short statement, SA Police said they were investigating the death of an infant at Glen Osmond and needed "more time to determine the nature and circumstances of the death".