CNN  — 

At least four people at a Bernie Sanders rally in Oakland rushed the stage Monday evening, spurring Secret Service agents to jump onto the raised platform and protect him.

The Democratic presidential candidate was uninjured and continued speaking, but not before several agents hugged him and pushed him away from the microphone. The identities of the individuals, who yelled as they approached the stage, were not immediately known. They were apprehended and led away by Secret Service from the podium at the Frank Ogawa Plaza, where the rally was being held.

After the events of Monday night in Northern California, Sanders spokesman Michael Briggs said, “It was handled professionally by the Secret Service.”

An animal rights group, Direct Action Everywhere, claimed responsibility for the disruption in a press release.

“Activists do not protest at Bernie Sanders rallies in opposition to Sanders himself, but rather to pull Sanders in their direction,” the group’s press release said. “Sanders’ opponent Hillary Clinton recently released a campaign platform on animal issues, although it stops far short of what activists would like to see. Activists expect Bernie Sanders, the progressive candidate, to support more radical action to provide animals not just with improved conditions but with legal rights to be free from harm.”

The Vermont senator began receiving Secret Service protection in early February during the early part of the presidential primary season, in his challenge to Democratic front-runner Hillary Clinton.

It’s not the first time in the 2016 campaign season that Secret Service have jumped on stage when commotion broke out around a protectee. In March a protestor jumped a barricade and tried to get on stage at a Donald Trump rally in Vandalia, Ohio, prompting Secret Service to react similarly by hopping on stage to shield the candidate.

Other security-related episodes have popped up around presidential candidates in recent months. In late April Donald Trump’s motorcade was forced to stop along a freeway, and Trump walked down a path, to get to a state GOP convention, in Burlingame, California.

Jane Sanders praised the agents’ response Tuesday in an interview with CNN’s Wolf Blitzer.

“The Secret Service are fantastic. I mean, they are just unbelievable in terms of being aware and protecting him,” Sanders said on “Wolf.” “So I’m very thankful for that. I think I heard it from breaking news and I called up – I didn’t see it – so I called up the campaign. I said, ‘What’s going on?’ They said, ‘Everything’s fine.’ So there was only maybe 60 seconds of concern.”

CNN’s Tom LoBianco contributed to this report.