The father of a 3-year-old boy who died after being found in a hot car in Sydney’s southwest has been released without charge.

The boy was found by his father in the car at about 3pm on Thursday as temperatures soared to 34C.

His dad punched a hole in the back window to get the boy out when he saw he was unconscious, a witness told the Daily Telegraph.

The boy was taken into a nearby store in an attempt to resuscitate him, however, when New South Wales Ambulance officers arrived the boy was unresponsive. He was pronounced dead at the scene.

Footage from the scene shows distraught people on the ground near the car.

A man was seen covering his face as he sobbed, with blood running down his right hand.

A police spokesman said the boy had been in the car all day.

A crime scene was established and an investigation into the circumstances surrounding the incident is underway.

The boy’s father was questioned by police over the incident but has been released without charge, a police spokesman told NCA NewsWire.

Child safety advocates Kidsafe claim more than 5000 children are rescued from hot cars in Australia every year - the majority being babies and toddlers.

“Leaving children unattended in a car - even for a short period of time - can be fatal,” reads information on Kidsafe’s website.

“Children are particularly at risk because they can lose fluid quickly, become dehydrated and suffer from heatstroke.”