NBC websites including those for the shows "Saturday Night Live" and "Late Night with Jimmy Fallon" were hacked Sunday by someone calling himself "pyknic," reports ZDNet.com. NBC’s main website was reportedly affected, along with sites for many of the network’s shows.

The sites started coming back Sunday afternoon, although the story notes that by 3:15 p.m. Eastern time some NBC sites were still down or broken. By Sunday evening, NBC’s websites appeared to be back to normal, according to a report from the Associated Press.

The hacker replaced the websites’ content with a screen of scrolling text that read, "Remember, remember the fifth of November. The gunpowder treason and plot. I know of no reason why the gunpowder treason should ever be forgot.”

The reference is apparently to Guy Fawkes Day, a British holiday that celebrates the failure of the 1605 "Gunpowder Plot" to blow up Parliament, which is celebrated on Nov. 5. The hackers group Anonymous often uses an image of Guy Fawkes as one of its symbols, the piece adds.