Protesters jumped barricades and interrupted a Bernie Sanders rally late Monday in Oakland.
The Democratic presidential hopeful was addressing supporters at Frank Ogawa Plaza at City Hall when at least four people hopped over barricades and attempted to rush the podium.
The group was stopped by Secret Service and agents also immediately surrounded Sanders during the incident.
Video appears to show a Secret Service agent strike one of the barricade jumpers several times with a night stick. The protesters were detained by authorities.
"We don't get intimidated easily," Sanders said after the incident.
Sanders' campaign said the group who jumped the barricades appear to be animal rights protesters.
Authorities said 20,000 people attended the rally, where Sanders donned a Golden State Warriors cap and told the crowd why he would be the best option for Democrats come November.
"In virtually every state and national poll, we do much better than Trump than Secretary Clinton does," he said.
But Sanders faces an uphill battle as his Democratic opponent Hillary Clinton is about 70 delegates away from clinching the nomination. A large number of those are superdelegates who could change their minds, and that's what Sanders and his supporters are banking on.
Sanders believes a win in California, a state with 475 delegates, would be a giant first step in the right direction.
"If there is a large voter turnout, we will win and win big," he told the gathering in Oakland.
Supporters aren't giving up either.
"He should stay in to the very last minute," said Joshua Harris, who was at the Oakland rally. "He should stay in as long as he can."
Another Sanders supporter, Jeff Nibert, agreed: "If California can send a message to the country next Tuesday, that would be a shocker around the world."
Earlier in the day, Sanders visited one of Oakland’s most influential black churches – Allen Temple Baptist along International Boulevard – with actor Danny Glover.
Sanders spoke to about 200 people inside the church, stressing economic equality and more access to education.
Sanders will be in Emeryville on Tuesday for a health care conference, followed by another rally in Santa Cruz. He'll wrap up his Bay Area tour Wednesday with a rally in Palo Alto.
Photo Credit: NBC Bay Area