As MSNBC went with live coverage all morning today of the nationwide school walk-outs against gun violence, Viacom channels went dark for 17 minutes at 10 a.m. ET in solidarity with the students.

The Viacom black-out will occur at 10 a.m. in every time zone as National School Walkout day continues, a month to the day that 17 students of Marjory Stoneman Douglas High School in Parkland, Florida, were murdered by a gunman with a semiautomatic rifle.

Today’s nationwide walk-out kicked off with students in Eastern time zones leaving their classrooms at 10 a.m., and the wave of walk-outs will follow the sun as 10 a.m. hits an estimated 3,000 schools across the nation. In Colorado, Columbine High School students will stage their walk-out and observe 30 seconds of silence – one second for each of the dead at Parkland and their own school – sometime around mid-day.

In Washington D.C., thousands had gathered outside the White House and on Capitol Hill by late morning, with MSNBC cameras capturing moments like students swarming Bernie Sanders as he spoke through a bullhorn. Elizabeth Warren and Charles Schumer visited earlier, and other politicians will no doubt drop by as the day goes on.

“Viacom stands with all students as they participate in the national school walkout against gun violence,” read the stark, white-letters-on-black-background message that took the place of regular programming on Comedy Central, VH-1, MTV, BET, Logo, TV Land and other Viacom channels.

On a Viacom company blog, the company posted an explanation for its 17-minute black-out – one minute for each of the slain Parkland students – that reads, in part:

Viacom and its brands have a long history of supporting young people’s movements around the world, and today the company is extending that tradition by leveraging its substantial multi-platform footprint to support these extraordinary individuals and amplify the reach and impact of their activism.

This series of efforts across MTV, BET, Nickelodeon, Paramount Network, Comedy Central, TV Land, CMT and other properties will include partnerships with a coalition of organizations and students that are working to make America’s schools safer and reduce gun violence.

Also today, students will take over MTV’s social media accounts.

Viacom’s efforts also include a $500,000 donation from Shari Redstone, Vice Chair of Viacom’s Board, to the March For Our Lives movement. Viacom also plans to devote extensive on-air and digital coverage of the March 24 March For Our Lives demonstration in Washington, D.C., like having MTV and Comedy Central change the color of their logos to orange (for gun violence awareness) for the 10 days prior to the march.

Programs and Viacom channels planning special or continued coverage leading up to the march include The Daily Show with Trevor Noah, The Opposition w/ Jordan Klepper, Paramount Network and Nickelodeon’s Kids’ Choice Awards, which airs March 24 and is expected to acknowledge the march in some way.

Though some school districts reportedly have pledged disciplinary action against walking students, thousands of students participated in the protest with official blessing, including many students interviewed by MSNBC reporters as they walked. (Fox News Channel wasn’t covering, at least on a continuous or extensive basis; CNN had stopped covering non-stop by 11:30 a.m. ET)