A retired Pennsylvania firefighter was arrested Thursday on federal charges that he threw a fire extinguisher that hit three Capitol Police officers during the violent siege on the Capitol last week.

Robert Sanford, 55, who retired last year from the Chester Fire Department, outside Philadelphia, turned himself in to the FBI to face charges that include assault of a police officer, disorderly conduct on Capitol grounds, civil disorder and unlawfully entering the Capitol.

Sanford, a supporter of President Donald Trump, got “caught up in the mob mentality,” his lawyer, Enrique Latoison, told The Associated Press.

The charges against Sanford are not related to the widely publicized attack on Officer Brian Sicknick, who also was assaulted with a fire extinguisher during the siege and who later died.

Sanford was held in Pennsylvania’s Lehigh County jail, where he had an initial court appearance by video Thursday and was denied bail.

Latoison argued to the judge that Sanford should be released on bail, citing his long service as a firefighter, his strong family ties and his lack of a criminal record. Sanford, a married father of three, did not go to Washington with weapons or the intent of rioting, and does not belong to any extremist groups, Latoison argued.

A federal prosecutor asserted in court - apparently in error - that a search of Sanford’s house Thursday turned up a T-shirt associated with the Proud Boys, a far-right group. Latoison told AP afterward that an inventory of the search listed no such T-shirt, and he said Sanford vigorously denied owning one. The prosecutor later acknowledged she had misspoken, blaming a miscommunication among FBI agents, Latoison said in a follow-up interview late Thursday.

“That’s a big mistake, and I’m not happy about it,” Latoison said. “I thought he was coming home until she came back with that.”

Noting the seriousness of the charges, the judge ordered Sanford to be held without bail, saying he presented a danger to the community.

Authorities said the case will be prosecuted in Washington.

The FBI asked the public this week to help identify a man seen in video stills who picked up a fire extinguisher and threw it at police outside the Capitol on Jan. 6. According to the charging documents, the extinguisher bounced off the heads of three officers, two of whom wore helmets.

Sanford, 55, traveled by bus with other people to the Capitol, according to documents. He told a friend when he returned home that he had been on the grounds for 10 minutes before leaving but did not mention throwing anything at officers, authorities said.

The friend saw the photos released by federal authorities and contacted police.

Latoison told AP that Sanford had attended Trump’s rally near the White House, in which the president told his supporters to walk to the Capitol and to “fight like hell” against the election results.

Without acknowledging Sanford’s guilt, Latoison said Sanford marched to the Capitol after Trump’s speech “and things got heated and he unfortunately got caught up.”

“People who seemingly are good people who have good intentions get themselves in a group, and then do something stupid they wouldn’t otherwise do,” he said.

“I’m not defending what happened,” Latoison added.

Sanford joined the Chester Fire Department in 1994 and retired nearly a year ago, according to city officials. He had an unblemished record, a city spokesperson said.

Mayor Thaddeus Kirkland called last week’s riot an act of domestic terrorism and said that if any city employee, current or former, took part in it, “then we hope our legal system will work according to its purpose and bring them to justice.”