Gov. Jared Polis signed a sweeping gun-control measure into law Thursday, the culmination of years of effort by advocates and progressive Democrats to limit the sale of high-powered semiautomatic weapons in Colorado.

Starting next summer, Coloradans will have to pass a background check and a training course before they can purchase a swath of semiautomatic firearms that include most of the guns known colloquially as assault weapons. Senate Bill 3 also prohibits the sale of bump stocks and rapid-fire trigger activators, which are firearm components that can increase a gun’s rate of fire.

The bill’s sponsors said it was intended to prevent future mass shootings and enforce the state’s existing prohibition on high-capacity magazines.

“We have been able to add to the safety of each and every Coloradan, especially when it comes to gun violence,” said Sen. Tom Sullivan, a Centennial Democrat who co-sponsored the bill with Sen. Julie Gonzales and Reps. Meg Froelich and Andy Boesenecker.

SB-3, which passed the legislature late last month, becomes the most sweeping gun-control measure passed by legislative Democrats in Colorado, and its passage into law was cheered Thursday by national gun-control groups Moms Demand Action and Everytown for Gun Safety.

Though the law doesn’t impose a complete ban on assault weapons or any type of firearm, it follows in the footsteps of previous attempts in the Capitol to fully prohibit the sale or purchase of those guns. A group of activists, including local students who’d repeatedly come to the state Capitol calling for tighter regulations, attended the bill signing in the governor’s office Thursday.