Connecticut will now limit the size of gun magazines to 10 rounds, expand the state's assault weapons ban and require universal background checks for all gun sales. NBC's Brian Williams reports.

With a green and white ribbon to commemorate the victims of one of the worst school shootings in American history pinned to his lapel, Connecticut Gov. Dan Malloy signed a broad new package of gun laws Thursday in the state where 20 children and 6 educators were slain nearly four months ago.

Connecticut is the third state, following Colorado and New York, to pass sweeping new gun legislation after the December school shooting.

“This is a profoundly emotional day, I think, for everyone in this room and everyone watching what is transpiring today in the state of Connecticut,” Malloy said before signing the bill. “We have come together in a new way that relatively few places in our nation have demonstrated an ability to do.”

Lawmakers had worked to forge a bipartisan consensus around the bill. The final package limited the size of gun magazines to 10 rounds, expanded the state's existing assault weapons ban, and required universal background checks on all gun sales in the state.

The bill passed by bipartisan majorities in both the Senate and the House.

“I’ve been amazed at the strength of the families since the day of Newtown,” Lt. Gov. Nancy Wyman said at the Thursday ceremony.

State Sen. John McKinney, a Republican who represents Newtown, said on Wednesday that the bill was an imperfect but necessary step in the wake of the Sandy Hook tragedy.

"The message we can send if those outside the walls of Connecticut are listening is encourage them to do the same, encourage our elected officials in Washington to put aside the politics and see if they can find some common ground," McKinney said Wednesday.

The Connecticut Citizens Defense League, a group that opposes gun control, denounced the new legislation in a post on its blog, saying that when the bill took effect Connecticut would have “the most unconstitutional gun laws in the entire country.”

Adam Lanza fired 154 rounds in fewer than 300 seconds after he entered the Newtown school armed with a Bushmaster .223 rifled and several 30-round magazines, according to investigators.

The shooting provoked a national outcry for tighter gun controls, but so far, with the exception of Colorado, New York and Connecticut, few states have made sweeping changes.

And a handful of states, such as Arkansas, Tennessee, and Kentucky, have gone the other direction, passing laws that would expand who can carry a gun and where.

President Obama pushed for a new federal law requiring more comprehensive background checks in a speech in Colorado on Wednesday. Obama said there “doesn’t have to be a conflict” between new gun laws and respect for gun rights.

Senator Chris Murphy, a Democrat, said the Connecticut bill provides an example to his fellow federal lawmakers on how to pass “tough, common sense gun laws.”

“The people of our state know that it takes bold, courageous action like this to help prevent the next tragic shooting,” Murphy said in a statement.

New York Gov. Andrew Cuomo, who led an aggressive January charge to tighten his state’s already strict laws, congratulated Connecticut lawmakers on Thursday “for taking bold new action to protect the people of their state.”

The mother of one of the school children killed at Sandy Hook Elementary School thanked Gov. Malloy at the Thursday signing. Nicole Hockley’s son Dylan was among the young students who died on December 14.

“While I am grateful for the progress being made, I wish more than anything that I were just back at home waiting till it was time for both Dylan and Jake to come home from school,” Hockley said.

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