HARTFORD — Governor Dannel P. Malloy signed sweeping new restrictions on weapons and large-capacity ammunition magazines Thursday in response to the Sandy Hook Elementary School massacre, a bipartisan deal that gun control proponents hope will spark action in Washington and state legislatures across the country.
Just four months ago, the governor broke the news to shocked parents that their children had been slaughtered in the Newtown school.
On Thursday, four of those parents joined him as he signed the bill during a somber ceremony at the state Capitol, his act giving Connecticut some of the toughest gun control laws in the country.
Malloy hugged each of the parents and gave them a pen he used to sign the bill.
‘‘We have come together in a way that relatively few places in our nation have demonstrated an ability to do,’’ he said.
Since the Dec. 14 shooting in which 20 children and six educators were killed at the school, some of their family members have become gun control advocates, pressing
for tougher state and federal laws.
‘‘This is a path I never thought my life would take. But working to save the lives of others is one way that I can honor Dylan’s life,’’ said Nicole Hockley, referring to her 6-year-old son who was killed at Sandy Hook. ‘‘We want Newtown to be known not for our tragedy but for transformation.’’
Malloy said he has become friends with some of the parents and promised to keep working with them to enact further law changes that address gun violence.
‘‘Today does not mark the end of our efforts,’’ Malloy said.
Malloy and gun control advocates said they hope the new law, crafted by legislative leaders from both parties during several weeks of negotiations, coupled with President Obama’s planned visit to the state Monday, will spur action in Washington.
Senator Richard Blumenthal, who still hopes that Congress can enact universal background checks for gun purchases, said many colleagues he has spoken to were deeply affected by the shooting.
‘‘They may not be there yet in their votes, but emotionally in their hearts they know what the right thing to do is and I’m hoping that they’ll be inspired by Connecticut to do the right thing,’’ he said.
In an interview on Fox News, Wayne LaPierre, the NRA’s executive vice president, criticized the legislation.
‘‘The problem with what Connecticut did is the criminals, the drug dealers, the people that are going to do horror and terror, they aren’t going to cooperate,’’ he said.
At the stroke of Malloy’s pen on Thursday, the new law added more than 100 firearms to the state’s assault weapons ban, effective immediately.
The new law also immediately bans the sale of magazines capable of holding more than 10 rounds of ammunition.
People who purchased those guns and magazines before midnight Wednesday will be allowed to keep them, so long as they are registered with the State Police before Jan. 1.
Required background checks for private gun sales also take effect.
Other parts of the new law that take effect over the coming year include a ban on armor-piercing bullets, establishment of a deadly weapon offender registry, expansion of circumstances when a person’s mental health history disqualifies them from holding a gun permit, mandatory reporting of voluntary hospital commitments, doubled penalties for gun trafficking and other firearms violations, and $1 million to fund the statewide firearms trafficking task force.
Members of Malloy’s administration met Thursday morning to discuss how to implement the legislation. Malloy said the affected state agencies plan to have everything in place by Aug. 1.
Connecticut lawmakers spent more than 13 hours debating the measure. Ultimately, the bill passed both chambers with bipartisan votes.
Some Connecticut lawmakers questioned whether the wide-ranging bill would have prevented 20-year-old Adam Lanza from blasting his way into his former elementary school.
‘‘These laws will only be obeyed by people who choose to obey them. Criminals will still have their guns and their magazines and they will still commit their crimes,’’ said state Representative Robert Sampson, a Republican.
‘‘Do we really think that adding more laws to our books would have stopped him?’’