OLYMPIA, Wash. (AP) - The state Senate has passed a ban on trigger modification devices that are designed to accelerate a firearm's rate of fire.

The measure to prohibit the devices, known as bump stocks, passed the chamber Thursday night on a 29-20 vote, with four Republicans voting with majority Democrats.

The move to ban the devices came in response to last October's mass shooting at a country music festival in Las Vegas that killed 58 people and left hundreds more injured.

Northwest News Network reports that the ban would make it illegal for anyone in Washington to manufacture or sell bump stocks beginning July 1. In July 2019, it would become illegal to own or possess a bump stock in Washington.

Democrats accepted an amendment from Republican Sen. Hans Zeiger - who voted for the final bill - that narrowed the definition of a trigger modification device.

The bill has not yet passed the House.