Just days ahead of a national day of action planned in response to last month's mass shooting that left 17 people dead at a high school in Florida, gun control advocates in Kentucky overnight hung 17 crosses—each marked with the name of one of the victims—from a large billboard in Louisville advertising one of the nation's largest gun shows.

The billboard was advertising the "National Gun Day Gun Show," an enormous weapons expo that brags being "the size of three football fields," which has a home in Louisville.

According the Louisville Courier Journal:

The names and ages of the victims of the shooting at Stoneman Douglas High School in Parkland, Florida, are written in black text on the crosses. It is unclear who is behind the crosses. The company that owns the billboard, Outfront Media, and the Kentucky Exposition Center did not immediately respond to emails seeking comment sent Sunday morning. It's the second billboard in the same stretch of freeway to be targeted since the Florida school shooting, as well as a school shooting in Marshall County, Kentucky, in January that left two people dead.

As of this writing, it remains unclear who is responsible for hanging the crosses from the billboard, but the Courier Journal reports other incidents in the area over the last year, including some by an individual or group tagging billboards with the phrase "Resist 45" and "Kill the NRA."

Gun-violence protesters hang 17 crosses from Louisville gun show billboard for Florida victims https://t.co/g5LCG8RNbQ pic.twitter.com/FxFyW3UP98 — Courier Journal (@courierjournal) March 11, 2018

On Wednesday of this week, March 14th, students across the country are planning a coordinated demonstration—called #Enough: National School Walkout—to demand major gun control reforms while also commemorating the victims of the massacre that took place at Marjory Stoneman Douglas High School on February 14 and all victims of gun violence.

Later in the month, on March 24th, students from Parkland and their allies are planning an even larger protest event—called March for Our Lives—that will include both events in local communities nationwide as well as a march in Washinton, DC.