The mother of four had a three-year-old son who was inside a sweltering vehicle for 20 minutes. Now she's issuing a warning to parents everywhere.

Amy Carey of Elkhart, in central Iowa, was working inside her home last week and she thought she knew where her three-year-old son Cason was. Unfortunately, he had slipped outside and into great danger. Here's her Facebook post which she issued as a warning to other parents.

We often hear the horrific stories of kids being left in vehicles and already several children have died in the U.S. this year. It was just over a week ago that it happened here in Iowa when a baby died in Des Moines, after being left in a hot car.

This is a very different reminder, and a good one. You may consider it unnecessary to lock the doors on your vehicle where you live. However, please do. It might save a life. Don't believe me? Last Thursday in Texas, a young boy died after going to get a toy from the back seat of a vehicle. Authorities believe he got in the front door, climbed over the seat, and then couldn't get out the back because child safety locks were on.

Over 660 children have died from heatstroke in the U.S. in unattended vehicles in the last 18 years. Amy Artuso, a program safety manager for the National Safety Council, told CNN that 29 percent of them were playing in a vehicle or got in themselves. Please lock those doors and tell others to do the same.