This is a serious question and hopefully this will not happen. However, if it does, there are several important steps to take.
First, the police officer should notify the chief of police, as the situation is very serious. As you know, Al-Qaeda is a serious organization bent on destroying our liberties and way of life. Moreover, I should not that this is time sensitive. This information should go up the chain of command immediately.
Second, Federal law enforcement should also be notified. They have more knowledge on these matters. When this happens, there will be more information sharing. At this point, these officials will come up with a plan of action.
I agree with all that was said about and I also have something small to add. I think that the federal agencies should work in conjuction with the Department of Defense and the Department of Homeland Security to figure out a course of action which might ultimately end in military invovlement. And I also pray to God that this never does happen to our country.