The incident occurred at a federal building in Los Angeles during a conference held by Secretary of Homeland Security Kristi Noem.
DHS officials said that Padilla tried to interrupt the conference. He was then detained by the Secret Service with the assistance of FBI uniformed police, who grabbed him before he could reach the podium. They eventually escorted him outside.
Video shows a Secret Service special agent on Noem's detail grabbing Padilla by his jacket and shoving him from the room, as the senator struggles to catch his breath while identifying himself.
"I'm Sen. Alex Padilla. I have questions for the secretary," he shouted in a halting voice. He tries to push back into the room when a second security guard appears.
Once out of the room, he can be heard shouting, "Hands off!"
One video posted online shows Padilla being forced to the ground by three officers and handcuffed by an officer wearing an FBI vest.
Padilla -- who is ranking member of the Senate Judiciary Immigration Subcommittee -- said he was trying to speak out about ICE detaining immigrants without criminal records.
His removal sparked strong reaction from many political leaders. Gov. Gavin Newsom described the act as "outrageous, dictatorial, and shameful."
A congressional oversight committee meeting descended into chaos after a screaming match broke out.
In the halls of Congress, a contingent of lawmakers, including South Bay Congressman Sam Liccardo, demanded a response from House Speaker Mike Johnson.
"Hey, everybody, I'm here outside the speaker's office. Speaker Johnson's inside," said Liccardo in a social media post.
Local community leaders were also quick to respond.
ABC7 News spoke with Christian Arana with the Latino Community Foundation. Arana said he's shocked by everything that happened.
"We still live in a democracy. This is still our right to speak up forcefully about what's happening in our country right now," Arana said.
DHS Assistant Sec. of Public Affairs Tricia McLaughlin said in a statement:
Senator Padilla chose disrespectful political theatre and interrupted a live press conference without identifying himself or having his Senate security pin on as he lunged toward Secretary Noem.
Mr. Padilla was told repeatedly to back away and did not comply with officers' repeated commands. @SecretService thought he was an attacker and officers acted appropriately.
Noem said she didn't know who Padilla was at the time of the incident.
Afterward, she told reporters she had a conversation with Padilla and even swapped numbers with him following the event.
"I wish that he would have reached out and identified himself and let us know who he was and that he wanted to talk. His approach was something that I don't think was appropriate at all," Noem said.
In a press conference, Padilla said that he was at the federal building in Los Angeles for a scheduled briefing, when he heard that Noem was holding a press conference "a couple of doors down the hall."
VIDEO: California Sen. Alex Padilla speaks after being forcibly removed from Noem press conference
California Sen. Alex Padilla speaks after being forcibly removed from Noem press conference
"I was there peacefully. At one point I had a question, and so I began to ask a question. I was almost immediately forcibly removed from the room. I was forced to the ground, and I was handcuffed. I was not arrested. I was not detained," Padilla said. "If this is how this administration responds to a senator with a question, if this is how the Department of Homeland Security responds to a senator with a question, you can only imagine what they're doing to farm workers, to cooks to day laborers out in the Los Angeles community and throughout California and throughout the country."
Padilla didn't take any questions after first addressing the media Thursday.
But he emphasized for those planning to protest in the coming days to remain peaceful and reject all forms of violence.
"We will hold this administration accountable," he said.
On Thursday evening, Rep. Eric Swalwell held a virtual press conference with members of the media.
"We now have a mad king who will arrest anyone who descends," Swalwell said.
ABC7 News asked if Senator Padilla's actions were 'political grandstanding.'
"Senator Padilla was doing his job in his own office building," Swalwell said. "He has an obligation to standup for his constituents who are being pulled out of their communities by these faceless masked agents and if Secretary Noem wasn't going to answer his question, he had a right to elevate his volume and his tone and demand an answer."
Rep. Zoe Lofgren called the incident outrageous.
"This is not the end, I'm afraid, but the beginning of the outrageous lawless action being undertaken by this administration and the abuse of the people of California," Lofgren said.
Many expect this incident will draw even more people to this weekend's "No Kings" protests.
The Associated Press contributed to this report.