'Cowards' billboard sends message to bombers

In the wake of Monday's Boston bombings, one theme has repeatedly appeared: "They messed with the wrong city."

The local chapter of the International Brotherhood of Electrical Workers echoed that sentiment using the most public means they could: a highway-side electric billboard off highway I-93.

"COWARDS," the billboard reads for 10 seconds. Then: "Pray for Boston."

"It was Local 103′s way of shouting out our feelings of anger," said IPEW business manager Michael P. Monahan.

None of the IPEW's 7,500 union members were hurt in Monday's explosions, the union told ABC News, but the chapter's headquarters is located in Dorchester, the same town that was the home of the bombing's youngest victim, eight-year-old Martin Richard.