As reported by the Seattle Times, Initiative 1491 has won easily:

With broad support across both sides of the Cascade Mountains, Initiative 1491, a gun-safety ballot measure, won easily.

In Tuesday night’s results, 71 percent of Washington voters were approving the initiative.

In King County, 83 percent of voters were approving the measure, according to an update overnight that added a smaller batch of votes to the tally. I-1491 also led in Kitsap, Mason, Thurston, Snohomish and Pierce counties, as well as Spokane and Okanogan counties. Only a handful of Eastern Washington counties were rejecting the measure.

Read their full breakdown here.