Suppose for a moment that it turns out someone really was carrying a gun on the VA Tech campus Thursday morning (which has yet to be determined). Would that be illegal?

Maybe not, according to NBC News correspondent Pete Williams.

The Virginia attorney general's office told Williams that "a public university generally cannot prohibit open or concealed carry of a firearm on campus grounds," even though a university can ban openly carried guns in campus buildings or at specified events.

But the state attorney general has determined that public universities cannot bar gun owners with valid concealed carry permits from bringing firearms into campus buildings.

"This is because Virginia's concealed carry law allows concealed carry permit holders to carry in places unless otherwise prohibited by law. A university's own campus policy does not have the force of law to prohibit concealed carry," said Brian Gottstein, a spokesman for Virginia's attorney general.

The Brady Campaign responded to Thursday's incident with a different take, obviously.

The Campaign said that if dozens of students and faculty had been armed on Virginia Tech’s campus, law enforcement’s ability to investigate the campers’ claims "would have been complicated and innocent people might have been harmed."

"If the Attorney General’s interpretation is allowed to stand, then many Virginia campuses could be regularly subject to people with guns roaming the campus, and law enforcement would be powerless to stop them -- until they start shooting," the Campaign said in a statement. "Just as we saw with the Tucson shooter, our weak gun laws, particularly our lax regulation of guns in public places, make it easy for people with evil intentions to walk into sacred public spaces with guns and cause disruption, confusion, and hysteria at the very least, while being free at the worst, to commit murder."

Last month, Virginia Attorney General Ken Cuccinelli claimed that the University of Virginia did not have the authority to ban people from bringing guns into school facilities, as long as they have concealed carry permits.

At the time, George Mason University officials believed their policy wouldn’t need to be changed. It restricts weapons in campus buildings and at campus events, which the officials say is specific enough.

Virginia Tech administrators, on the other hand, planned to meet with the school’s board of visitors to decide if language needed to be revised on its policy of banning weapons.