'Disturbing' lockdown nursery rhyme in kindergarten class goes viral

A kindergarten class in Somerville, Massachusetts, has a poster of nursery rhyme set to the tune of “Twinkle, Twinkle, Little, Star” to prepare for an active shooter situation.

The poster went viral after Georgy Cohen tweeted a photo of it Wednesday.

“This should not be hanging in my soon-to-be-kindergartener’s classroom,” Cohen wrote.

“Lockdown, lockdown, lock the door. Shut the light off, say no more,” the rhyme reads. “Go behind the desk and hide; wait until it’s safe inside. Lockdown, lockdown, it’s all done. Now it’s time to have some fun!”

The nursery rhyme was seen as “disturbing” and “necessary” to many online.

"It's too bad our kids have to be taught this, it's terrible," a parent told the local news.

Following this year's Parkland, Florida, school shooting that killed 17 people and the Santa Fe, Texas, school shooting that killed 10, schools at all levels have had to plan and prepare for the worst-case scenario.

"I think the trainings are perfect, and I think the schools are doing exactly what they're supposed to do to make sure our kids are protected," another parent said.