Some Facebook users were having trouble logging into their accounts Monday night, getting a message that their accounts were "temporarily unavailable" because of a "site issue."
"We expect this to be resolved shortly. Please try again in a few minutes."
NBC News contacted Facebook, and will update this post when we hear back. Right now, it's not known how many people are having the log-in problem, but some took to Twitter to share their concern.
"Lots of people are having trouble," said Twitter user @taytaysinger16, responding to a question about the problem from NBC News' Helen A.S. Popkin. When she posed the same question on Facebook, a handful of people replied that they'd had a problem.
It is not clear if the problem, whatever it was, affected any mobile Facebook pages.