SAN FRANCISCO, Jan. 26 (Xinhua) -- Washington state in the U.S. west pacific region has passed a bill to ban modification of the trigger of automatic weapons to prevent possible massacre that occurred in a U.S. state last year, a local TV reported Friday.

The bill that cleared the Washington state Thursday night will make it illegal for anyone in the state to modify the trigger devices of automatic weapons, known as bump stocks, to operate more like automatic weapons.

Such modification would accelerate a firearm's rate of fire to make automatic weapons more powerful and leathal, according to a live-fire experiment shown in the footage of the local K5 News TV.

The Senate's measure was seen as a response to a mass shooting in Las Vegas, a resort city in the U.S. western state of Nevada, in October last year, which killed 58 people and injured hundreds of more other revelers at a country music festival.

The ban, which will take effect on July 1 this year, bans manufacturing or selling of bump stocks in the state, and in July 2019, it would become illegal for anyone to own or possess a bump stock in Washington.