National Walkout Day: NRA posts photo of AR-15 one month after Parkland shooter used AR-15

Show Caption Hide Caption Students across country walk out to demand change This is what a nationwide walkout looks like.

On Wednesday morning, as students nationwide protested to mark the one-month anniversary of the high school shooting in Parkland, Fla., the National Rifle Association promoted a glamorized image of an AR-15 — the same kind of gun used to kill 17 people in the massacre.

"I'll control my own guns, thank you," the NRA tweeted at 11:30 a.m. ET, as students' walkout demonstrations rippled across the United States.

Many students, such as those at Marjory Stoneman Douglas High School, where last month's shooting occurred, said they walked out Wednesday to gain visibility as they push for lawmakers to ban assault rifles like the one used in the shooting.

The AR-15 image came from an NRA article praising the weapon as "the musket of its era." Unlike muskets, which fired about one round every 20 seconds, AR-15-style rifles have become the favorite gun of mass shooters looking to fire about one round every half second.

Several mass shootings have relied on AR-15-style guns, including: Parkland, Sutherland Springs, Texas; Las Vegas; Orlando; and Newtown, Conn.

Florida lawmakers voted against a proposal to halt sales of the gun in the wake of the Parkland shooting.

More: Why the AR-15 keeps appearing at America's deadliest mass shootings

The tweet was sent on the same day that thousands of students across an estimated 2,800 schools participated in Wednesday's National Walkout Day. Many students left their classrooms at 10 a.m. local time for 17 minutes — one minute for each victim in Parkland's attack.

The event is part of a series of nationwide demonstrations that will include a massive rally called March For Our Lives set for March 24 in Washington.

More: Nickelodeon went off the air for 17 minutes at the time of the national walkout

More: Powerful photos of the walkout from across the nation