Several illuminated electronic devices planted at bridges and other spots caused a security scare in Boston.
Most of the devices depicted a character making an obscene gesture in what turned out to be a US publicity campaign for a late-night cable television cartoon.
Roads, bridges and a section of the Charles River were shut down and bomb squads were sent in before authorities declared the devices were harmless.
Peter Berdovsky (27) and Sean Stevens (28) were charged last night with one count of placing a hoax device and one count of disorderly conduct, said state Attorney General Martha Coakley.
Turner Broadcasting, a division of Time Warner and parent of Cartoon Network, said the devices were part of a promotion for the TV show Aqua Teen Hunger Force, a surreal series about a talking milkshake, a box of fries and a meatball.
Authorities are investigating whether Turner and any other companies should be criminally charged, Ms Coakley said.
Police display one of the electronic devices yesterday
Mr Berdovsky and Mr Stevens were scheduled to be arraigned today in Charlestown District Court.
"We're not going to let this go without looking at the further roots of how this happened to cause the panic in this city," Ms Coakley said at a news conference.
Those conducting the campaign should have known the devices could cause panic because they were placed in sensitive areas, she said.
Mr Berdovsky told The Boston Globe earlier that he was an artist and installed the devices for an advertising company hired by Turner. He described himself as "a little kind of freaked out," the Globe reported.
Mayor Thomas Menino said the security scare may have cost the city more than $500,000. At least 14 of the devices were found, and at least 24 more were still around the city, officials said.
AP