After a terrifying crib-related incident, an Arizona mom is sharing an important message about safety.

On April 4, Alison Johnson posted a Facebook photo of her 18-month-old twins' cribs, along with her frightening story and PSA.

"I have a lot of friends that have twins or kids close in age that may have a similar set up, so I wanted to share something VERY scary that happened today," Johnson began her post.

The mom said that morning, she put her son Caleb down for a nap in his crib, which is located next to his twin sister Libby's crib. A few minutes later, he started to cry, and when Johnson entered the room to check on him, she saw he had climbed out of his crib and gotten trapped between his crib and Libby's.

"His body fit through, but his head wouldn't," the mom wrote. "He was using every ounce of energy he had to hold himself up by his little arms. If they had given out, he would've just been hanging there by his head."

Johnson's PSA has been shared almost 50,000 times. In a follow-up post , she said she was "pleasantly surprised" to have received mostly positive, gratitude-filled responses and very few negative comments.

"People can be so terrible on the Internet, especially when it comes to mom judging, but I figured if our experience could possibly save a life, I'd take the grunt of it from the Internet trolls," she wrote.

Instead, Johnson received "hundreds of messages from twin moms" who changed the way their nurseries were set up after reading the post.

"Kindness ... it's a nice change of pace for social media!" she wrote.

H/T PopSugar