A band of out-of-state “domestic terrorists” was accused Saturday of planning to attack President Barack Obama’s campaign headquarters and Mayor Rahm Emanuel’s home — and firebomb police stations and squad cars — declaring that after the NATO Summit “the city will never be the same,” police and prosecutors said.

One of the conspirators warned: “The city doesn’t know what it’s in for,” prosecutors said.

But undercover Chicago Police officers infiltrated the group of NATO Summit protesters in recent weeks. They were with the protesters while they allegedly made Molotov cocktails — bottles filled with flammable liquid that are used as firebombs, sources said.