California officials on Thursday said the state has appealed a federal judge's decision to strike down its three-decade-old ban on assault-style weapons, saying the law is needed to prevent gun deaths.

The appeal challenges last week's ruling from U.S. District Judge Roger Benitez of San Diego that the law illegally infringes upon the U.S. Constitution's Second Amendment, which guarantees the right of citizens to bear arms.

Governor Gavin Newsom and Attorney General Rob Bonta told a news conference outside a San Francisco hospital they were confident the decision was flawed and would eventually be overturned.

"We're better than this," said a visibly frustrated Newsom, who also sharply criticized the judge.

The state will ask the appeals court to put the ruling on hold during the appeal; Benitez stayed his order from taking effect for 30 days, leaving the law in place for now.

California became the first state to ban assault weapons in 1989 in the wake of a school shooting that killed five children. Six other states and the District of Columbia have an assault weapons ban in place, according to the gun safety group Giffords.

A federal assault weapons ban expired in 2004, and Congress has not re-authorized the law in the face of Republican opposition.

Guns are a politically sensitive issue in the United States, which has the highest rate of gun ownership of any country, as well as a higher incidence of gun violence than other wealthy nations.

Two weeks ago, a gunman opened fire at a San Jose rail yard, killing nine people, part of a spate of high-profile mass shootings in Indiana, Colorado and Georgia, among other states.