A traffic sign from the city of Austin, Texas was broken into by unknown individuals who altered the displayed message to read “Zombies Ahead.” According to some hackers, the signs can be tampered with easily because their control panels are regularly left open and the default access password is not changed.

The signs near the intersection of Lamar and MLK usually warn drivers about upcoming construction, but Monday morning they warned passers by to beware of zombies. A city spokesperson says the hacked messages were only up for a few hours, until the construction project manager saw them during his morning commute and immediately ordered them to be changed back.

Sara Hartley, a spokeswoman for the public works department, confirmed that the culprits had cut through a padlock on one sign to gain access to the computer system, which was then hacked. "Even though this may seem amusing to a lot of people, this is really serious, and it is a crime," she explained. "And you can be indicted for it, and we want to make sure our traffic on the roadways stays safe."

The stunt is a Class C misdemeanor punishable by a $500 fine, she told an Austin TV station. She also said she did not know whether any other signs in the area had been altered.

But in spite of it all, the motorists who saw it did not run for their lives, but found the message hilarious. For instance, Wayne Haggard, owner of Sterling Construction, the company that installed the signs, thought it was amusing: "It's Austin. We have a sense of humor. Let it go," he told a local TV station.