(CNN) Washington state is seeking to reduce gun violence by making it tougher to buy assault rifles.

As of January 1, purchasers of semi-automatic rifles in the Evergreen state must be 21 or older.

The new law raises the minimum age from 18 and comes after almost 60% of Washingtonians voted in November in favor of a ballot measure to place restrictions on sales of semi-automatic weapons.

The age restriction is one of a number of new gun-control measures within Initiative 1639, but the first to take effect.

On July 1, the remaining provisions of the ballot initiative will become law. They include enhanced background checks and a 10-day waiting period for semi-automatic rifle purchases. Buyers of such guns will also need to have completed a firearm safety-training course within the last five years.

Read More