Federal officials say that security measures across the country will be increase ahead of the July 4th holiday weekend.

Police say that they are concerned about ISIS sympathizers in the country who might heed the group’s call for major terror attacks during the month of Ramadan.

New York Congressman Peter King told ABC there was “great concern” about terror attacks and that it was unusual for officials to put out warnings so far in advance of a holiday unless they had major reason for concern.

“ISIS is incomparable as far as terrorist organizations as far as being able to reach,” King said on “This Week.” “They can reach the disaffected, they can reach the deranged, they can also reach the ideologically committed.”

King is not alone in his concern.

“I wouldn’t be surprised if we’re sitting here a week from today talking about an attack over the weekend in the United States. That’s how serious this is,” Former CIA deputy director Michael Morrell told CBS News.

The warnings come on the heels of three coordinated terrorist attacks in Europe that were claimed by ISIS.