Sweltering in Philly took on new meaning Monday as supporters of Bernie Sanders vented their anger at the email scandal that cost party chair Debbie Wasserman Schultz her job -- then turned up the heat at the opening of the Democratic National Convention.

The protesters marched toward the convention site from City Hall downtown, with the crowd numbering close to 2,000 by late afternoon. 

By late afternoon, hundreds of demonstrators were face to face with police on bikes. Five were taken into custody and placed in plastic handcuffs after they jumped a barrier that was erected just moments earlier. In total, dozens reportedly were taken into custody. But city police later said there had been no arrests; rather, 55 had been cited for disorderly conduct. 

Inside the convention hall, boos also broke out among Sanders supporters as they jeered at the very mention of Hillary Clinton’s name. 

As the protesters gathered outside City Hall earlier in preparation for the march, volunteers handed out water to demonstrators as an oppressive heat wave hit the region. The National Weather Service forecast temperatures hitting the high 90s on Monday but feeling 100-plus degrees with the humidity factored in.

Despite the heat, demonstrators took up the cause -- coming from Florida to Philly and everywhere between.

Amanda Sullivan of Weston, Fla., told FoxNews.com she traveled north to take part in the demonstrations after experiencing voter suppression during the Democratic primaries.

“How violating, how absolutely dehumanizing,” Sullivan said.

Sullivan claims state Democratic officials gave her a hard time after she tried to vote for Sanders. She said she complained and even sent a letter to DNC CFO Brad Marshall but was ignored – and says it’s one of the reasons she has become frustrated with the process.

Monday’s rallies, for some Sanders supporters, turned into a victory march following the stunning and sudden resignation of Florida Rep. Debbie Wasserman Schultz as the Democratic Party’s chairwoman.

On Sunday, Wasserman Schultz resigned following furor over thousands of leaked emails that seemed to show Democratic National Committee members tipping the scales in favor of Clinton during the primaries.

The uproar was a blow to Democrats who had hammered Republicans over their lack of unity at last week’s convention in Cleveland. On Thursday, Donald Trump formally accepted the Republican nomination. Police had anticipated protests and riots ahead of the Republican convention though only a few popped up.

Sullivan says the WikiLeaks email scandal reaffirms her fears that the party may be permanently fractured.

“For us, who have been watching the whole thing unfold… we already knew the system was rigged,” Sullivan said. “It wasn’t a surprise. To us, it was ‘Do you believe us now?’”

In one of the largest rallies planned for Monday, a pro-Bernie Sanders group walked four miles across the Ben Franklin Bridge, which connects New Jersey and Philadelphia.  

Naomi Craig, who drove down from West Minster, Vt., said despite her opposition to Republican candidate Donald Trump, she won’t vote for Clinton.

“I’m scared of Trump but I’m not not scared of Hillary,” Craig told FoxNews.com.

Jared Foster of Joanna, S.C., brought his son, A.D. 15, and his friend Mentrez Davis, 15, to Philadelphia as a teachable moment.

“It’s good to get experience in activism,” A.D. told FoxNews.com. “Coming from South Carolina – it’s a very red state and to meet people who are like-minded is neat.”

Quintin Lynch of Enterprise, Ore., said he was throwing his support behind Green Party presumptive presidential candidate Jill Stein. 

"We don't stand a chance in hell with Hillary Clinton or Donald Trump," he said. "I was never about Bernie. He was a leader but not the leader of the movement."

Multiple grassroots organizations have come to Philadelphia in an effort to get their voices heard.

One such organization, Democracy Spring, asked supporters online if they were willing to get cuffed for the cause.  

On their website, they want supporters to sign a pledge that includes the line: “I pledge to risk arrest with hundreds of others doing nonviolent civil disobedience at the DNC in Philly between July 25-28.”

On Sunday, police estimated between 5,000 and 10,000 people attended rallies -- already surpassing the number of protestors at the RNC convention in Cleveland.

Pasu Tivorat, of Sacramento, who wore a Guy Fawkes mask, told The New York Times Trump and Clinton were both bad choices.

“If we nominate Hillary, then she can continue to abuse her base,” he said. “Every progressive idea we come up with they throw under the bus.”

He added, “I’d rather watch the D.N.C. burn,” he added.

FoxNews.com's Joseph Weber and Adam Shaw contributed to this report.