Microsoft co-founder and Seattle real estate mogul Paul Allen donated $1 million to a new initiative that would enact tougher restrictions on the sale of semiautomatic weapons in Washington state.

Allen, along with venture capitalist Nick Hanauer and other donors, helped raise nearly $3 million for the campaign. The Alliance for Gun Responsibility says Washington voters will have the chance to vote on Initiative 1639 in November. Allen tweeted his support for the initiative Monday.

My statement on a gun safety initiative in my home state of Washington: Initiative 1639 is a reasonable and necessary measure that will improve the safety of our schools and our communities, which is why I have contributed a million dollars to the campaign. 1/2 — Paul Allen (@PaulGAllen) May 21, 2018

I hope people throughout the state will support the campaign, so that we can qualify and pass this important initiative into law. 2/2 — Paul Allen (@PaulGAllen) May 21, 2018

If passed, the initiative would raise the minimum age to purchase semiautomatic rifles to 21 and create more enhanced background checks, bringing the system in line with requirements to purchase handguns. The initiative would also require people to undergo firearm safety training before purchasing a semiautomatic weapon and require a waiting period of up to 10 days to purchase the weapon.

In 2014, Allen donated $500,000 to a separate initiative to expand background checks on all gun sales in Washington state.

On Friday, a shooting in Santa Fe, Texas, left 10 dead and 10 more injured. It came just three months after 17 people died in the Parkland, Fla., shooting in which students became vehement advocates of gun reform.