Three illuminated road signs were hacked overnight, city officials said, and warnings about road work changed to mild obscenities.

Portland spokeswoman Jessica Grondin said the message boards on Brighton Avenue and Frost and Capisic streets, alerting drivers to road construction near Capisic Pond, were accessed sometime early Wednesday morning.

Grondin said signs on Frost and Capisic streets contained messages that were mildly obscene, including one that read “you suck,” after someone opened a case containing a keyboard on the rear of the signs. She said the sign on Brighton Avenue was spotted by a Maine Department of Transportation worker early Wednesday and changed first – she said she doesn’t know what it read before it was spotted.

The signs are owned and operated by Sargent Corp., the road work contractor, she said, and were all changed around 4 a.m. They were changed back to the correct messages by 7 a.m., she said.

The cabinets containing the keyboards that control the sign messages weren’t locked, Grondin said, but Sargent is now locking them and adding password protection to prevent the signs from being changed again.

Grondin said the sign changes appeared to be the work of juveniles, given the messages that were posted. Four years ago, a hacker put a little more thought and humor into the effort, when a sign on Auburn Street was altered to read, “Warning Zombies Ahead!”