She was unpacking her car when the door slammed. Then began one of her most terrifying life moments.

Emily Atkins had just parked in the driveway of her home in Melbourne’s north-east after a trip to the local shops with her two-year-old daughter Sylvie – and a carload of shopping bags – in tow.

It was a warm summer’s morning in Heidelberg North. The temperature was set to climb above 30 degrees that day, but at 10.30am hadn’t reached its top yet.

As Emily told Mamamia she had one of those cars that allowed her to lock the car before she closed all the doors, and she would use this to her advantage to lock the car and slip it in her bag before getting out and have both hands free for carrying in bags.

That day though, this technology would work against her.

Listen: There’s also a risk bigger kids will drive off if left with the keys, as these parents found out. (Post continues.)

“Just without thinking, being octopus arms, and trying to get all the shopping and the kid (out of the car), I chucked my keys on the seat of the car, shut the door and then the car auto-locked with the keys inside.”

“She was in the car and so were my keys and I just thought ‘oh my goodness, this could go really, really wrong’.

“It was pretty terrifying just to have that realisation of how quickly it could happen and how easily.”

Thankfully, Emily’s husband had only just left for work and was able to turn around and open the door and let her out within 10 minutes.

“Otherwise I would have been in a situation where I had to call the RACV or even the SES to get her out,” the mum-of-two said.

“I was lucky that I had my handbag out, so I did have my phone. If I didn’t have a phone I would had to have gone and found a neighbour and left her alone in the car. It was panic stations.”

Unfortunately, it's a nightmare scenario thousands of Australian parents face every year. In Victoria in 2017 alone, the Royal Automobile Club of Victoria's roadside assistance answered 1150 calls outs to rescue young children locked in vehicles. This works out to an average of four incidents per day. According to the RACV, most of these cases were accidental, and that developments in locking technology mean it's a mistake becoming increasingly easy to make.

That's why they're putting out a timely warning to parents on the risks of locking their kids in cars on hot days.

RACV road user behaviour manager Melinda Spiteri said the dangers of children left unattended in cars on hot days was very real.

"Research has shown that younger children are more sensitive to heat than older children and adults, as their body temperatures rise five times faster than an older child’s," she said.

"This means they are at high risk of dehydration and heatstroke when trapped in a hot car.

"Knowing the dangers vehicle lock-ins pose to young children, RACV treats call-outs of this nature as urgent. However, drivers should be aware that the few minutes it can take for a patrol to reach the scene can make all the difference in extreme temperatures."

Melinda advised parents against giving their children keys to play with, and suggested keeping your keys on a lanyard on all car trips with the kids during summer, adding that Victorian families could be pick up a free lanyard from their local RACV shop.

Emily said before it happened to her, she hadn't considered the possibility, and cautioned people against thinking this mistake was something they weren't capable of making.

"I think it's a really dangerous assumption that it could never happen to you. It's so simple. It just takes a split second."

Now, Emily says she takes extra precautions to keep Sylvie, now four, and her four-month-old sister Violet safe in cars.

"As soon as I turn the ignition off I keep my keys in my hand, so I wear the keyring as a ring... or I'll put it in my pocket and I'll pat it to double cement in my head that that's where they are"

"The other thing is that I make sure not all the doors are shut in my car before I've gotten the kids out. Just in case, on the off chance that something stupid does happen, they're not in there.

"I can lock my handbag in there and deal with the consequences, but with the loves of my life, there's no way anymore."

For more information about RACV's Check Keys – Check Kids campaign visit the RACV webiste.