WATCH: Sade Baderinwa was live in the media tent during the sit-in protest:
Some supporters had their mouths taped shut. A few others sang "This Land is Your Land" and held a banner that read, "We The People."
Bernie delegate protestors tape their mouths shut to symbolise their voices not being heard at the #DemConvention pic.twitter.com/PeglMsdpjd
— Sabrina Sayeed (@sab_sayeed) July 26, 2016
They say they're holding a peaceful protest to complain about being shut out by the Democratic Party.
Bernie Sanders delegates have walked out! Holding a sit in now! #DemsInPhilly #FeelTheBern pic.twitter.com/MmH7WtzyMq
— ToastyPoptart (@LollipopCrumbs) July 26, 2016
One protester is 64-year-old Talat Khan, of San Bernardino, California.
He says: "It's for the betterment of our children and the future of our children."
In the midst of the sit-in protest, one woman silently celebrated Hillary Clinton's historical nomination.
This woman silently celebrating first female presidential candidate of major party in midst of pro Bernie sit-in pic.twitter.com/WbSjFr68Nx
— Quinn Bowman (@quinnbowman) July 26, 2016
Earlier Tuesday, Sanders asked the convention to nominate Clinton by acclamation. The delegates did so, to wild cheers inside the Wells Fargo Center.
(Some information from the Associated Press)