ALBANY, N.Y. – Jumping out ahead of Washington, New York state enacted the nation’s toughest gun restrictions Tuesday and the first since the Connecticut school massacre, including an expanded assault-weapon ban and background checks for buying ammunition.

Democratic Gov. Andrew Cuomo signed the measure into law less than an hour after it won final passage in the Legislature, with supporters hailing it as a model for the nation and gun-rights activists condemning it as a knee-jerk piece of legislation that won’t make anyone safer and is too extreme to win support in the rest of the country.

“Common sense can win,” Cuomo said. “You can overpower the extremists with intelligence and with reason and with common sense.”

Owners of an estimated 1 million previously legal semiautomatic rifles, such as the Bushmaster model used to kill 20 children and six adults in Newtown, Conn., a month ago, will be allowed to keep their weapons but will have a year to register them with police. The sale of any more such weapons is prohibited.

“When there’s a pileup of events, when the federal government does not do it, the state of New York has to lead the way,” said state Assemblyman Joseph Lentol, a Brooklyn Democrat and co-sponsor.

In addition to outlawing a broader array of military-style weapons, the measure restricts ammunition magazines to seven rounds, down from the current 10, creates a more comprehensive database of people barred from owning guns, and makes New York the first state to require background checks to buy bullets. The system will also help flag customers who buy large amounts of ammo.

In another provision, therapists, doctors and other mental health professionals will be required to tell state authorities if a patient threatens to use a gun illegally. The patient’s weapon could then be taken away.

Richard Aborn, president of the Citizens Crime Commission of New York City, said Cuomo clearly understood gun violence is a complex issue requiring broader solutions than simply banning a particular weapon. “I think that’s an important message for the nation,” he said.

In a statement, the National Rifle Association said: “These gun control schemes have failed in the past and will have no impact on public safety and crime.

“While lawmakers could have taken a step toward strengthening mental health reporting and focusing on criminals, they opted for trampling the rights of law-abiding gun owners in New York, and they did it under a veil of secrecy in the dark of night.”