What does 1 Thessalonians 5:3 mean?

People will be saying, 'Everything's fine, we're safe,' and then, out of nowhere, disaster will crash down on them—like labor pains that hit a pregnant woman. There's no way to escape it. 1 Thessalonians 5:3 - Modern Text Bible

(Many will feel secure, but sudden judgment will come, unavoidable and surprising.)