WASHINGTON -- The shooting of Rep. Gabrielle Giffords is a watershed event in many ways, some of which we cannot yet know, but one of the clearest and simplest is this: Congress and its members are about to be permanently quarantined, physically isolated, from the people it and they represent.

Thirty years ago, there was no such thing as security on Capitol Hill or for members. Members of the public were free to roam the halls, and police presence was practically invisible. There were no barricades around the grounds, and even the leadership rarely had any form of protection.

The Hill was the very model of the People's Place -- and in that respect it was an inspirational symbol of our democracy.

Congress began to close in on itself in 1983. A bomb explosion outside the Senate chamber engendered the installation of magnatometers; in 1998 a gunman shot two Capitol Police in an attack in the House. The result was a system of careful monitoring of all visitors and the extension of police protection to all members of the leadership. The 9/11 attacks led to the erection of barricades and new defense perimeters around the grounds; new inspection procedures were initiated after an anthrax attack in 2003 on the offices of then-Democratic leader Tom Daschle's office.

The construction of a new Visitor Center now means that the public can only enter through a secure facility and can only walk the halls in tour groups.

New even more restrictive rules are now inevitable. It's even possible that the general public will be banned from the hallways of the Capitol Complex, at least at certain times and under certain circumstances.

As for personal protection, that is likely to be increased substantially. For the last year or two, some House members and senators have had unpublicized but substantial security details dispatched to their side when deemed warranted.

The Huffington Post has learned that one Democratic senator had a special security detail detailed to him for two weeks after concerns were raised about personal threats.

But rather than have extensive details for each member, the members are likely to change their behavior -- which means they will stay behind closed doors here in DC and in their home districts and states.

Following the shooting of Rep. Gabrielle Giffords on Saturday the U.S. Capitol Police issued the following statement and guidance to lawmakers:

"Federal, state and local law enforcement authorities in Arizona are investigating a shooting in Tucson, Arizona in which Congresswoman Gabrielle Giffords was shot. Multiple others were shot as well. Congresswoman Giffords has been transported to a local medical facility with serious injuries. The suspect is in custody. No further details on the motive or other victims are available at this time." "The U.S. Capitol Police are directly involved in this investigation. As more information is developed, it will be provided. In the interim, all Members and staff are advised to take reasonable and prudent precautions regarding their personal security."