Turns out, it was a publicity stunt. According to the AP:
At least nine electronic devices, planted at bridges and other parts of Boston as part of a marketing campaign for a late-night cartoon, threw a scare into the city Wednesday.The general reaction in the newsroom: ohmygawd. What were they thinking?
Highways, bridges and a section of the Charles River were shut down and bomb squads were sent in before authorities declared the devices were harmless.
"It's a hoax — and it's not funny," said Gov. Deval Patrick.
Turner Broadcasting, parent company of Cartoon Network, said the devices, which consisted of magnetic, blinking lights, were part of a promotion for the TV show "Aqua Teen Hunger Force."
You have to wonder.