USA TODAY STAFF

PHILADELPHIA—They wanted their message to be heard. So they took it where they knew it would be: a tent filled with hundreds of members of the media.

Supporters of Vermont Senator Bernie Sanders walked out of the Democratic National Convention on Tuesday evening, timing their angry protest to the official nomination of Hillary Clinton. The exodus came moments after a surprise appearance at the convention site by Jill Stein, the Green Party's presidential candidate, who was quickly surrounded by a chanting crowd that included both messages of support and insults by delegates.

Hundreds of demonstrators abandoned their seats as the convention floor erupted in a celebration of Clinton's nomination. Sign-waving protesters flowed through the concourse, then joined in a minutes-long stream that poured out of the building. Many marched into a nearby media tent, which was then sealed off temporarily by Philadelphia and Pennsylvania State police.

"What does democracy look like?" some shouted. "This is what democracy looks like," answered the moving line of protesters.

They held signs with messages of revolution and the "rigged" system. Some wore tape or tied fabric across their mouths to signify that they're being silenced. Reporters with cameras and cell phones circled around the protesting delegates, conducting interviews and live-streaming the action. Judith Cashin Lerma, a nurse and Sanders delegate from Texas, said the protest is about a change, a revolution. "He said from the beginning this is not about him,"" she said. "We decided to vote with our feet." A large contingent of police officers stood by but did not take any action to remove them. The officers blocked the doors, preventing more delegates and members of the media from getting in. But after about an hour, the protesting delegates left the tent and congregated outside the arena instead. The scene outside the arena was peaceful, but demonstrators expressed anger and frustration, claiming Clinton won due to unfair tactics and voter fraud.