PHILADELPHIA (KCBS) – Bernie Sanders delegates shouted down speakers at a California Democratic Party breakfast on the opening day of the Democratic National Convention, after WikiLeaks posted Democratic National Committee emails disparaging Sanders.

KCBS reporter Doug Sovern reported the delegates backing Sanders booed when presumptive Democratic nominee Hillary Clinton was mentioned. Sanders supporters also argued with Clinton supporters at the breakfast.

Remarkable scene at CA #DNCinPHL breakfast: majority are here for Clinton, but crowd BOOING Hillary, chanting Bernie pic.twitter.com/7KUQTeRkoK — Doug Sovern (@SovernNation) July 25, 2016

Sanders delegates shouted down California Secretary of State Alex Padilla when he spoke, chanting “count the votes.” In May, a Sanders supporter sued Padilla, accusing elections officials of disenfranchising voters unaffiliated with a political party. At the time, Padilla called the lawsuit “frivolous” and a federal judge rejected the suit.

Simply amazing: irate Bernie delegates drown out @CASOSvote Padilla as he tries to address CA delegation pic.twitter.com/4H4Uam4waF — Doug Sovern (@SovernNation) July 25, 2016

Rep. Mike Honda (D-San Jose) was also shouted down during his speech.

Attendees were mostly quiet when House Minority Leader Nancy Pelosi spoke to the California delegation. Pelosi drew cheers from Sanders supporters when she said, “I don’t take it as a discourtesy, even if it is intended as one.”

• ALSO READ: Sanders’ Call For Clinton Support Greeted With Jeers

After speaking, Pelosi told reporters that the protest among Sanders supporters was “interesting, even entertaining” but said there is no threat to party unity after WikiLeaks posted nearly 20,000 DNC emails late last week.

SF's @NancyPelosi: Rowdy Bernie rebellion at CA delegation is "interesting, even entertaining" but no unity threat pic.twitter.com/bd2dZWHyj9 — Doug Sovern (@SovernNation) July 25, 2016

Several emails showed DNC officials scoffing at Sanders and his supporters while he was battling with Clinton for the nomination. In once email, a staffer questioned Sanders’ religious beliefs.

While WikiLeaks did not disclose the source of the emails, the DNC announced last month that Russia hacked into the committee’s computers. Clinton’s campaign has blamed the hacking on the Russians.

Protesters also booed DNC chair Debbie Wasserman Schultz at a breakfast of the Florida delegation Monday morning. Wasserman Schultz plans to resign this week in the wake of the email controversy.

Hours after the breakfast, the Senator from Vermont was jeered by his supporters in a speech where he urged them to vote for the former Secretary of State in November. Sanders is scheduled to speak on the convention floor in a primetime address Monday night.