A new law in Washington state banning the sale of semiautomatic assault rifles to anyone under the age of 21 went into effect on Tuesday, part of a sweeping new gun control initiative voted into law in November.

Voters in the state overwhelmingly chose to rein in access to firearms as part of Initiative-1639, which included provisions for tougher background checks, mandatory safe storage of guns and an increase in age for semiautomatic assault rifles. The measure also mandates gun safety training and a 10-day waiting period. It passed with 59 percent support.

Only the age portion of the law took effect on Jan. 1, according to The Associated Press. The other provisions will become law in July.

As part of the legislation, a semiautomatic assault rifle is defined as any rifle that uses “a portion of the energy of a firing cartridge to extract the fired cartridge case and chamber the next round.” Antique firearms, guns that have been made inoperable, and manually operated weapons using a bolt, pump, lever or slide action are excluded from the designation.

Washington state joins several others that have moved to limit access to semiautomatic weaponry following a spate of mass shootings in recent years, many of which have involved such firearms. Hawaii, Illinois, Vermont and New York ban the sale of all guns to anyone under 21, and many states require gun owners to be at least 18 to buy a semiautomatic assault rifle.

The proposal, however, has already drawn condemnation from gun rights advocates. Gun sellers in Washington have joined forces with the National Rifle Association and the Second Amendment Foundation to sue the state in an attempt to overturn the law.

“The gun lobby is trying to thwart the will of nearly 60 percent of Washingtonian voters who supported common sense gun reform in our state,” Washington Attorney General Bob Ferguson said in a statement. He added that he looked “forward to representing the people of the state of Washington in court against the NRA.”

This story has been updated to include the definition of semiautomatic assault rifles under Washington state’s new law.