Alison Johnson posted a photo on Facebook of her twin babies’ cribs, which are set up side-by-side.

“This morning I put Caleb down for his nap. Shortly after he started to cry. After a few minutes, I went to check on him,” Johnson wrote.

>> Click here to read her post

She says she will forever remember what she saw next. He managed to climb over the edge of his crib, but got stuck in the space between his crib and his sister’s.

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

Johnson said she usually uses the babies’ nap time as a chance to take a shower.

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“Had I done that today and check on him after five minutes, he would have literally hung himself,” she wrote. “When baby proofing, I never in a million years would have seen this as a potential danger.”

She warned other parents not to make the same mistake she did.

“It’s incredibly heartbreaking to think of what the outcome could have been today,” Johnson wrote.

Dolce's favorite time of the day! #SnackTime #EyeOnThePrize 😋😋😋

Posted by Alison Johnson on Sunday, April 3, 2016