OLYMPIA, Wash. (AP) — The Washington House amended and passed a bill to ban trigger devices that allow semi-automatic rifles to fire more rapidly.

The bill moved on a 56-41 vote Friday after the chamber accepted an amendment that would allow the Washington State Patrol to set up a "buy back" program for people who already own the devices, known as bump stocks.

The measure now heads for a final vote in the Senate, which passed the underlying measure last month on a 29-20 vote.

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. 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.